Amsterdam Rules (synthesis [1950, 2014])

I. International rules of botanical nomenclature.

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Chapter I. General Considerations and Guiding Principles (Art. 1—9).

Art. 1. Botany cannot make satisfactory progress without a precise system of nomen-
clature, which is used by the great majority of botanists in all countries.

Art. 2. The precepts on which this precise system of botanical nomenclature is based
are divided into principles, rules and recommendations. The principles (Art. 1—9, 10—14, 15—19¹)
form the basis of the rules and recommendations. The object of the rules (Art. 19—74) is to
put the nomenclature of the past into order and to provide for that of the future. They are
always retroactive: names or forms of nomenclature contrary to a rule ( illegitimate names or
forms) cannot be maintained. The recommendations deal with subsidiary points, their object
being to bring about greater uniformity and clearness especially in future nomenclature; names
or forms contrary to a recommendation cannot on that account be rejected, but they are not
examples to be followed.

Art. 3. The rules of nomenclature should be simple and founded on considerations
sufficiently clear and forcible for everyone to comprehend and be disposed to accept.

Art. 4. The essential points in nomenclature are: (1) to aim at fixity of names; (2) to
avoid or to reject the use of forms and names which may cause error or ambiguity or throw
science into confusion.

Next in importance is the avoidance of all useless creation of names.

Other considerations, such as absolute grammatical correctness, regularity or euphony
of names, more or less prevailing custom, regard for persons, etc., notwithstanding their un-
deniable importance are relatively accessory.

Art. 5. In the absence of a relevant rule, or where the consequences of rules are doubtful,
established custom must be followed.

Art. 6. Botanical nomenclature is independent of zoological nomenclature in the sense
that the name of a plant is not to be rejected simply because it is identical with the name of an
animal. If, however, an organism is transferred from the animal to the plant kingdom, its validly
published names are to be accepted as botanical nomenclature in the form prescribed by the
rules of botanical nomenclature, and if an organism is transferred from the plant to the animal
kingdom, its names retain their status in botanical nomenclature.

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1) Art. 19 is both a principle and a rule.

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Art. 7. Scientific names of all groups are usually taken from Latin or Greek. When
taken from any language other than Latin, or formed in an arbitrary manner, they are treated
as if they were Latin. Latin terminations should be used so far as possible for new names.

Art. 8. Nomenclature deals with: (1) the terms which denote the rank of taxonomic
groups (Art. 10—14); (2) the names which are applied to the individual groups (Art. 15—71).

Art. 9. The rules and recommendations of botanical nomenclature apply to all classes
of the plant kingdom, recent and fossil, with certain distinctly specified exceptions.

Chapter II. Categories of taxonomic groups, and the terms denoting them

(Art. 10—14, Rec. I, II).

Art. 10. Every individual plant, interspecific hybrids and chimaeras excepted, belongs
to a species (species), every species to a genus (genus), every genus to a family (familia), every
family to an order (ordo), every order to a class (classis), every class to a division (divisio).

Art. 11. In many species, varieties (varietas), forms (forma), and races or biological
forms (forma biologica) are distinguished; in parasitic species special forms (forma specialis),
and in certain cultivated species modifications still more numerous; in many genera sections
(sectio) are distinguished, in many families tribes (tribus).

Recommendation I. In parasites, especially parasitic fungi, authors who do not give specific value
to forms characterized from a biological standpoint but scarcely or not at all from a morphological standpoint, should
distinguish within the species special forms (forma specialis) characterized by their adaptation to different hosts.

Art. 12. Finally, if a greater number of intermediate categories are required, the terms
for these subdivisions are made by adding the prefix sub (sub) to the terms denoting the
categories. Thus subfamily (subfamilia) denotes a category between a family and a tribe,
subtribe (subtribus) a category between a tribe and a genus, etc. The classification of
subordinated categories may thus be carried, for wild plants, to twenty-three degrees in
the following order: Regnum vegetabile. Divisio. Subdivisio. Classis. Subclassis. Ordo.
Subordo. Familia. Subfamilia. Tribus. Subtribus. Genus. Subgenus. Sectio. Subsectio.
Species. Subspecies. Varietas. Subvarietas. Forma. Forma biologica. Forma specialis.
Individuum.

If this list of categories is insufficient it may be augmented by the intercalation of
supplementary categories, provided that this does not introduce confusion or error.

Examples: Series and subseries are categories which may be intercalated between subsection and species.

Recommendation II. The arrangement of species in a genus or in a subdivision of a genus is made
by means of typographic signs, letters or numerals.

The arrangement of subspecies under a species is made by letters or numerals; that of varieties by the
series of Greek letters α, β, γ, etc. Groups below varieties and also half-breeds are indicated by letters, numerals
or typographic signs at the author’s will.

Art. 13. The definition of each of these categories varies, up to a certain point, accord-
ing to individual opinion and the state of the science; but their relative order, sanctioned by
custom, must not be altered. No classification is admissible which contains such alterations.

Examples of inadmissible alteration: a form divided into varieties, a species containing genera, a genus containing
families or tribes: e. g. Huth (in Engl. Bot. Jahrb. XX: 337, 1895) divided the subgenera of Delphinium into “tribes”.

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Art. 14. The fertilization of one species by another may give rise to a hybrid
(hybrida); that of a subdivision of a species by another subdivision of the same species
may give rise to a half-breed (mistus).

Chapter III. Names of taxonomic groups (Art. 15—72, Rec. III–L).

Section 1. General principles; priority (Art. 15—17, Rec. III).

Art. 15. The purpose of giving a name to a taxonomic group is not to indicate the
characters or the history of the group, but to supply a means of referring to it.

Art. 16. Each group with a given circumscription, position and rank can bear only
one valid name¹), the earliest that is in accordance with the Rules of Nomenclature.

Art. 17. No one may change a name (or combination of names) without serious motives,
based either on more profound knowledge of facts or on the necessity of giving up a nomenclature
that is contrary to the Rules.

Recommendation III. Changes in nomenclature should be made only after adequate taxonomic study.

Section 2. The type method (Art. 18, Rec. IV—VII).

Art. 18. The application of names of taxonomic groups is determined by means of
nomenclatural types. A nomenclatural type is that constituent element of a group to which the
name of the group is permanently attached, whether as an accepted name or as a synonym. The
name of a group must be changed if the type of that name is excluded (see Art. 66).

The type of the name of an order or suborder is a family, that of the name of a family,
subfamily, tribe or subtribe is a genus, that of a generic name is a species, that of the name of
a species or group of lower rank is usually a specimen or preparation. In some species, however,
the type is a description or figure given by a previous author. Where permanent preservation
of a specimen or preparation is impossible, the application of the name of a species or subdivision
of a species is determined by means of the original description or figure.

Note: the nomenclatural type is not necessarily the most typical or representative element of a group; it
is merely that element with which the name of the group is permanently associated.

Examples: the type of the name Malvales is the family Malvaceae; the type of the name Malvaceae is the genus
Malva; the type of the name Malva is the species Malva sylvestris L.; the type of the name Polyporus amboinensis Fries is
the figure and description in Rumph. Herb. Amboin. VI, p. 129, t. 57, fig. 1.

Recommendations :

IV. When publishing names of new groups, authors should indicate carefully the subdivision which is
the type of the new name; the type-genus in a family, the type-species in a genus, the type-variety or specimen in
a species. This type determines the application of the name in the event of the group being subsequently divided. When
describing new species, varieties or forms of parasitic plants, especially Fungi, the host plant of the type should be indicated.

V. When revising a genus, an author should state which species he accepts as the nomenclatural type.

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1) In genera and groups of higher rank, the valid name is the earliest name published with the same rank,
provided that this is in conformity with the Rules of Nomenclature and the provisions of Arts. 20 and 21.

In subdivisions of genera the valid name is the earliest name published with the same rank provided that this
name and its combination with the generic name are in conformity with the Rules of Nomenclature.

In species and groups of lower rank, the valid name is the binary or ternary combination containing the earliest
epithet published with the same rank, provided that this combination is in conformity with the Rules of Nomenclature.

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VI. In selecting a nomenclatural type for a genus of non-vascular Cryptogams, botanists should, where
possible, choose a species that will fix the generic name as it is now commonly applied.

Examples: Hypoxylon Fr. (Summa Veg. Scand. 383—4). Fries first used the name for a genus to include
25 species now distributed in Ustulina, Anthostoma, Nummularia, Daldinia, Sordaria, etc. To take the first species,
H. ustulatum as the type would displace the name Ustulina, and most of the other species which are now known as
Hypoxylon would require another generic name. If, however, H. coccineum, species No. 11 in Fries’s list, a well-known
and widely-distributed species, be taken as the type, the name Hypoxylon would be retained in its present general
application and the nomenclature would be stabilized. — The genus Valsa Fr. (Summa Veg. Scand. 410) contained 44
species now placed in several different genera. The first species V. Sorbi is now known as a species of Eutypella. By
selecting V. ceratophora Tul. (V. decorticans Fr.) the name Valsa is retained in its present general application and
many nomenclatural changes are avoided ¹).

VII. The utmost importance should be given to the preservation of the original (“type”) material on which
the description of a new group is based. In microscopic Cryptogams the preparations and original drawings, in fleshy
Fungi water-colour drawings and specimens suitably prepared or dried, should be preserved. The original account should
state where this material is to be found.

Section 3. Limitation of the principle of priority: publication, starting-points,

conservation of names (Art. 19—22).

Art. 19. A name of a taxonomic group has no status under the Rules, and no claim to
recognition by botanists, unless it is validly published (see Section 6, Art. 37).

Art. 20. Legitimate botanical nomenclature begins for the different groups of plants
at the following dates: —

(a) Phanerogamae and Pteridophyta, 1753 (Linnaeus, Species Plantarum, ed. 1).

(b) Muscineae, 1801 (Hedwig, Species Muscorum).

(d) Lichenes, 1753 (Linnaeus, Species Plantarum, ed. 1).

(e) Fungi: Uredinales, Ustilaginales and Gasteromycetes, 1801 (Persoon, Synopsis
methodica Fungorum).

(f) Fungi caeteri, 1821—32 (Fries, Systema mycologicum).

(g) Algae, 1753 (Linnaeus, Species Plantarum, ed. 1).

Exceptions. — Nostocaceae homocysteae, 1892—93 (Gomont, Monographie des Oscillariées,
in Ann. Sci. Nat. Bot. sér. 7. VI: 91, VII: 263). — Nostocaceae heterocysteae, 1886—93
(Bornet et Flahault, Revision des Nostocacées hétérocystées in Ann. Sci. Nat. Bot. sér. 7. III: 323,
IV: 344, V: 51, VII: 177). — Desmidiaceae, 1848 (Ralfs, British Desmidieae). — Oedogoniaceae,
1900 (Hirn, Monographie und Iconographie der Oedogoniaceen in Act. Soc. Sci. Fenn. XXVII,
No. 1).

(h) Myxomycetes, 1753 (Linnaeus, Species Plantarum, ed. 1).

The nomenclature of fossil plants of all groups begins with the year 1820.

It is agreed to associate generic names which appear in Linnaeus’s Species Plantarum,
ed. 1 (1753) and ed. 2 (1762—63) with the first subsequent descriptions given under those
names in Linnaeus’s Genera Plantarum, ed. 5 (1754) and ed. 6 (1764).

The two volumes of Linnaeus, Species Plantarum, ed. 1 (1753), which appeared in
May and August, 1753, respectively, are treated as if they had been published simultaneously
on the former date.

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1) Numerous cases of this kind might be cited among the Fungi. Following the above recommendation would
largely obviate the need of a lengthy list of nomina conservanda.

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Example: Thea L. Sp. Pl. ed 1, I (May 1753) and Camellia L. Sp. Pl. ed 1, II (Aug 1753) are treated as if they
had been published simultaneously in May 1753. Under Art. 56, the combined genus bears the name Camellia, since Sweet
(Hort. Suburb. Lond. 1818, 157), who was the first to unite the two genera, chose that name, citing Thea as a synonym.

Art. 21. However, to avoid disadvantageous changes in the nomenclature of genera
by the strict application of the Rules of Nomenclature, and especially of the principle of priority
in starting from the dates given in Art. 20 the Rules provide a list of names which must be
retained as exceptions. These names are by preference those which have come into general
use in the fifty years following their publication, or which have been used in monographs and
important floristic works up to the year 1890.

Note 1. These lists of conserved names will remain permanently open for additions. Any proposal of an
additional name must be accompanied by a detailed statement of the cases for and against its conservation. Such proposals
must be submitted to the Executive Committee, who will refer them for examination to the Special Committees for the
various taxonomic groups ¹).

Note 2. The application of conserved names is determined by nomenclatural types, or by substitute-types where
necessary or desirable.

Note 3. A conserved name is conserved against all other names for the group, whether these are cited in the
corresponding list of rejected names or not, so long as the group concerned is not united or reunited with another group
bearing a legitimate name. In the event of union or reunion with another group, the earlier of the two competing names
is adopted in accordance with Art. 56.

Note 4. A conserved name is conserved against all earlier homonyms.

Examples. — The generic name Spergularia J. et C. Presl (1819) is conserved against Alsine L. (1753), emend.
Reichb. (1832) (= Delia Dum. + Spergularia), although Alsine L. (1753), partim, is not included in the list of rejected names:

Spergularia was conserved as including Delia (Alsine L., partim). — If the genus Weihea Spreng. (1825) is united with
Cassipourea Aubl. (1775), the combined genus will bear the prior name Cassipourea although Weihea is conserved, and
Cassipourea is not. — If Mahonia Nutt. (1818) is reunited with Berberis L. (1753), the combined genus will bear the prior
name Berberis, although Mahonia is conserved. — Nasturtium R. Br. (1812) was conserved only in the restricted sense, for
a monotypic genus based on N. officinale R. Br.: hence, if it is reunited with Rorippa Scop. (1760), it must bear the name

Rorippa. — The generic name Swartzia Schreb. (1791), conserved in 1905 against Tounatea Aubl., Possira Aubl. and Hoel-
zelia Neck., is thereby conserved automatically against the earlier homonym Swartzia Ehrh. (1787).

Art. 22. When a name proposed for conservation ²) has been provisionally approved
by the Executive Committee, botanists are authorised to retain it pending the decision of the
next International Botanical Congress.

Section 4. Nomenclature of the taxonomic groups according to their categories

(Art. 23—35, Rec. VIII—XX).

§ 1. Names of groups above the rank of family.

Recommendations :

VIII. Names of divisions and subdivisions, of classes and subclasses, are taken from their chief characters.
They are expressed by words of Greek or Latin origin in the plural number, some similarity of form and termination
being given to those which designate groups of the same nature.

Examples: Angiospermae, Gymnospermae, Monocotyledoneae, Dicotyledoneae, Pteridophyta, Coniferae. Among
Cryptogams old family names such as Fungi, Lichenes, Algae, may be used for names of groups above the rank of family.

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1) See list of Nomina conservanda proposita.

2) There is also a list of Nomina conservanda familiarum (Art. 23; Appendix II).

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IX. Names of orders are preferably taken from the name of one of their principal families, with the ending -ales.
Suborders are designated in a similar manner, with the ending -ineae. But other terminations may be used for these names,
provided that they do not lead to confusion or error.

Examples of names of orders: Polygonales (from Polygonaceae), Urticales (from Urticaceae), Glumiflorae, Centro-
spermae, Parietales, Tubiflorae, Microspermae, Contortae. Examples of names of suborders: Bromeliineae (from Bromeliaceae),
Malvineae (from Malvaceae), Tricoccae, Enantioblastae.

§ 2. Names of families and subfamilies, tribes and subtribes.

Art. 23. Names of families are taken from the name of one of their genera, or from
a synonym, and end in -aceae.

Examples: Rosaceae (from Rosa), Salicaceae (from Salix), Caryophyllaceae (from Caryophyllus, a pre-Linnean
genus).

Exceptions: (1) The following names, sanctioned by long usage, are treated as excep-
tions to the rule: Palmae, Gramineae, Cruciferae, Leguminosae, Guttiferae, Umbelliferae, Labiatae,
Compositae. Botanists are authorised, however, to use as alternatives the appropriate names
ending in -aceae. (2) Those who regard the Papilionaceae as constituting an independent family
may use that name, although it is not formed in the prescribed manner.

To avoid disadvantageous changes in the nomenclature of families by the strict appli-
cation of the Rules and especially of the principle of priority, a list of names which must be
retained as exceptions will be provided (Appendix II).

Art. 24. Names of subfamilies (subfamiliae) are taken from the name of one of the
genera in the group, with the ending -oideae, similarly for tribes (tribus) with the ending -eae,
and for subtribes (subtribus) with the ending -inae.

Examples of subfamilies: Asphodeloideae (from Asphodelus), Rumicoideae (from Rumex); tribes: Asclepiadeae
(from Asclepias), Phyllantheae (from Phyllanthus); subtribes: Metastelmatinae (from Metastelma), Madiinae (from Madia).

§ 3. Names of genera and subdivisions of genera.

Art. 25. Names of genera are substantives (or adjectives used as substantives), in the
singular number and written with an initial capital, which may be compared with our family

names. These names may be taken from any source whatever, and may even be composed in
an absolutely arbitrary manner.

Examples: Rosa, Convolvulus, Hedysarum, Bartramia, Liquidambar, Gloriosa, Impatiens, Manihot, Ifloga (an
anagram of Filago).

Recommendation X. Botanists who are forming generic names show judgment and taste by attending
to the following recommendations: —

(a) Not to make names very long or difficult to pronounce.

(b) Not to dedicate genera to persons quite unconnected with botany or at least with natural science nor to
persons quite unknown.

(c) Not to take names from barbarous languages, unless those names are frequently cited in books
of travel, and have an agreeable form that is readily adaptable to the Latin tongue and to the tongues of
civilised countries.

(d) To indicate, if possible, by the formation or ending of the name the affinities or analogies of the genus.

(e) To avoid adjectives used as nouns.

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(f) Not to give to a genus a name whose form is rather that of a subgenus or section (e. g. Eusideroxylon, a name
given to a genus of Lauraceae. This, however, being legitimate, cannot be altered).

(g) Not to make names by combining words from different languages (nomina hybrida).

(h) To give a feminine form to all personal generic names, whether they commemorate a man or a woman.

Art. 26. Names of subgenera and sections are usually substantives resembling the

names of genera. Names of subsections and other lower subdivisions of genera are preferably
adjectives in the plural number agreeing in gender with the generic name and written with an
initial capital, or their place may be taken by an ordinal number or a letter.

Examples. — Substantives: Fraxinaster, Trifoliastrum, Adenoscilla, Euhermannia, Archieracium, Micromeli-
lotus, Pseudinga, Heterodraba, Gymnocimum, Neoplantago, Stachyotypus. — Adjectives: Pleiostylae, Fimbriati, Bibracteolata.

Recommendations :

XI. Botanists constructing names for subgenera or sections will do well to attend to the preceding recom-
mendations and also to the following: —

(a) To give, where possible, to the principal subdivision of a genus a name which recalls that of the genus
with some modification or addition. Thus Eu may be placed at the beginning of the generic name when it is of Greek
origin, -astrum, -ella at the end of the name when Latin, or any other modification consistent with the grammar and
usages of the Latin language.

Examples: Eucardamine (from Cardamine), Trifoliastrum (from Trifolium), Drabella (from Draba).

(b) To avoid giving to a subgenus or a section the name of the genus to which it belongs, with the ending -oides
or -opsis: but on the contrary to reserve this ending for a section which resembles another genus and by then adding
-oides or -opsis to the name of that other genus, if it is of Greek origin, to form the name of the section.

(c) To avoid taking as the name of a subgenus or section a name which is already in use as such in another
genus, or which is the name of a genus.

(d) To avoid in co-ordinated subdivisions of a genus the use of names in the form of a noun together with
those in the form of a plural adjective; the former should be used chiefly for subgenera and sections, the latter for sub-
sections, series and subseries.

XII. When it is desired to indicate the name of a subgenus or section (or other subdivision to which a parti-
cular species belongs) in connexion with the generic name and specific epithet, the name of the subdivision is placed in
parenthesis between the two (where necessary, the rank of the subdivision is also indicated).

Examples: Astragalus (Cycloglottis) contortuplicatus; Loranthus (Sect. Ischnanthus) gabonensis.

§ 4. Names of species (binary names).

Art. 27. Names of species are binary combinations consisting of the name of the genus
followed by a single specific epithet. If an epithet consists of two or more words, these must
either be united or joined by hyphens. Symbols forming part of specific epithets proposed by
Linnaeus must be transcribed.

The specific epithet, when adjectival in form and not used as a substantive, agrees
in gender with the generic name.

Examples. — Cornus sanguinea, Dianthus monspessulanus, Papaver Rhoeas, Uromyces Fabae, Fumaria Gussonei,
Geranium Robertianum, Embelia Sarasinorum, Atropa Belladonna, Impatiens noli-tangere, Adiantum Capillus-Veneris. —

Scandix Pecten ♀ L. must be transcribed as Scandix Pecten-Veneris; Veronica Anagallis ∇ L. must be transcribed as Veronica

Anagallis-aquatica. — Helleborus niger, Brassica nigra, Verbascum nigrum.

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Recommendations :

XIII. The specific epithet should, in general, give some indication of the appearance, the characters, the
origin, the history or the properties of the species. If taken from the name of a person, it usually recalls the name of the
one who discovered or described it, or was in some way concerned with it.

XIV. Names of men and women and also of countries and localities used as specific epithets, may be substan-
tives in the genitive (Clusii, saharae) or adjectives (Clusianus, dahuricus). It will be well, in the future, to avoid the use of
the genitive and the adjectival form of the same epithet to designate two different species of the same genus: for example
Lysimachia Hemsleyana Maxim. (1891) and L. Hemsleyi Franch. (1895).

XV. In forming specific epithets botanists will do well to have regard also to the following re-
commendations: —

(a) To avoid those which are very long and difficult to pronounce.

(b) To avoid those which express a character common to all or nearly all the species of a genus.

(d) To avoid, in the same genus, epithets which are very much alike, especially those which differ only in their
last letters.

(e) Not to adopt unpublished names found in travellers’ notes or in herbaria, attributing them to their authors,
unless these have approved publication.

(f) Not to name a species after a person who has neither discovered, nor described, nor figured, nor in any
way studied it.

(g) To avoid epithets which have been used before in any closely allied genus.

(h) To avoid specific epithets formed of two or more (hyphened) words.

(i) To avoid epithets which have the same meaning as the generic name (pleonasm).

§ 5. Names of groups below the rank of species (ternary names).

Art. 28. Epithets of subspecies and varieties are formed like those of species and follow
them in order, beginning with those of the highest rank. When adjectival in form and not used
as substantives they agree in gender with the generic name.

Similarly for subvarieties, forms and slight or transient modifications of wild plants,
which receive either epithets or numbers or letters to facilitate their arrangement. The use of
a binary nomenclature for subdivisions of species is not admissible. It is permissible to reduce
more complicated names to ternary combinations.

Examples: Andropogon ternatus subsp. macrothrix (not Andropogon macrothrix or Andropogon ternatus subsp.
A. macrothrix); Herniaria hirsuta var. diandra (not Herniaria diandra or Herniaria hirsuta var. H. diandra); Trifolium stellatum
forma nanum (not nana). Saxifraga Aïzoon subforma surculosa Engl. et Irmsch. is permissible for Saxifraga Aïzoon var.
typica subvar. brevifolia forma multicaulis subforma surculosa Engl. et Irmsch.

Art. 29. The same epithet may be used for subdivisions of different species, and the
subdivisions of one species may bear the same epithet as other species.

Examples: Rosa Jundzillii var. leioclada and Rosa glutinosa var. leioclada; Viola tricolor var. hirta in spite of
the existence already of a different species named Viola hirta.

Art. 30. Two subdivisions of the same species, even if they are of different rank,
cannot bear the same subdivisional epithet, unless they are based on the same type. If the earlier
subdivisional name (ternary combination) was validly published, the later one is illegitimate
and must be rejected.

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Examples: The ternary combinations Biscutella didyma subsp. apula Briq. and Biscutella didyma var. apula
Halácsy (see Briquet, Prodr. Pl. Corse. II: 107, 108, 1913) may both be used because they are based on the same type, and
the one includes the other.

The following is incorrect: Erysimum hieraciifolium subsp. strictum var. longisiliquum and E. hieraciifolium
subsp. pannonicum var. longisiliquum — a form of nomenclature which allows two varieties bearing the same name in the
same species.

Andropogon Sorghum subsp. halepensis var. halepensis Hack. is permissible: the two subdivisions bearing the
same epithet but representing subordinate grades based on the same type, A. halepensis Brot., and thus being synonymous
except that the epithet of the lower subdivision is used in a restricted sense.

Recommendations :

XVI. Recommendations made for specific epithets apply equally to epithets of subdivisions of species.

XVII. Special forms (forma specialis) are preferably named after the host species; if desired, double names
may be used.

Examples: Puccinia Hieracii f. sp. villosi; Pucciniastrum Epilobii f. sp. Abieti-Chamaenerii.

XVIII. Botanists should avoid giving a new epithet to any subdivision of a species which includes the
type either of a higher subdivisional name or of the specific name. They should either repeat that epithet, with or
without a prefix, or use one of the customary epithets, typicus, genuinus, originarius, etc.

Examples: Andropogon caricosus subsp. mollissimus var. mollissimus Hackel; Arthraxon ciliaris subsp. Langs-
dorfii var. genuinus Hackel.

XIX. Botanists proposing new epithets for subdivisions of species should avoid such as have been used previ-
ously in the same genus, whether for species or for subdivisions of other species.

§ 6. Names of hybrids and half-breeds.

Art. 31. Hybrids or putative hybrids between species of the same genus are designated
by a formula and, whenever it seems useful or necessary, by a name.

(1) Sexual hybrids. The formula consists of the names or specific epithets of the two
parents in alphabetical order and connected by the sign ×. When the hybrid is of known experi-
mental origin, the formula may be made more precise by the addition of the signs ♀, ♂, the name
of the female (seed-bearing) parent being placed first.

The name, which is subject to the same rules as names of species, is distinguished
from the latter by the sign × before the name.

(2) Asexual hybrids (graft hybrids, chimaeras, etc.). The formula consists of the names of
the two parents in alphabetical order and connected by the sign +. The name has a “specific”
epithet different from that of the corresponding sexual hybrid (if any), and is preceded by
the sign +.

Examples of sexual hybrids: Salix capreola (Salix aurita × caprea), Digitalis lutea ♀ × purpurea ♂; Digi-
talis purpurea ♀ × lutea ♂.

Example of asexual hybrids: + Solanum tubingense (Solanum Lycopersicum + nigrum).

Art. 32. Bigeneric hybrids (i. e. hybrids between species of two genera) are also
designated by a formula and, whenever it seems useful or necessary, by a name.

The formula consists of the names of the two parents connected by a sign, as in Art. 31.

The name consists of a new “generic” name usually formed by a combination of the
names of the parent genera, and a “specific” epithet. All hybrids (whether sexual or asexual)
between the same two genera bear the same “generic” name.

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(1) Sexual hybrids. In the formula the connecting sign × is used. The name is pre-
ceded by the sign ×.

(2) Asexual hybrids. In the formula the connecting sign + is used. The name is pre-
ceded by the sign +. The “specific” epithet is different from that of the corresponding sexual
hybrid (if any) between the same species.

Examples of sexual hybrids: × Odontioda Boltonii (Cochlioda Noezliana × Odontoglossum Vuylstekeae);
× Pyronia Veitchii (Cydonia oblonga × Pyrus communis).

Examples of asexual hybrids: + Laburnocytisus Adami (Laburnum + Cytisus purpureus); + Pyronia
Daniellii (Cydonia oblonga + Pyrus communis).

Art. 33. Ternary hybrids, or those of a higher order, are designated like ordinary
hybrids by a formula and, whenever it seems useful or necessary, by a binary name. Such as
are trigeneric or polygeneric are given new “generic” names usually formed by a combination
of the names of the parent genera.

Examples: × Salix Straehleri = Salix aurita × cinerea × repens or S. (aurita × repens) × cinerea.

Examples of new generic names: × Brassolaeliocattleya (composed of the three names Brassavola, Laelia and
Cattleya); × Potinara; × Vuylstekeara.

Recommendation XX. Half-breeds or putative half-breeds may be designated by a name and a
formula. Names of half-breeds are intercalated among the subdivisions of a species, and are preceded by the
sign ×. In the formula the names of the parents are in alphabetical order. When the half-breed is of known ex-
perimental origin, the formula may be made more precise by the addition of the signs ♀, ♂, the name of the female
(seed-bearing) parent being placed first.

Art. 34. When different hybrid forms of the same parentage (pleomorphic hybrids;
combinations between different forms of a collective species, etc.) are united in a collective group,
the subdivisions are classed under the binary name of the hybrid like the subdivisions of a species
under that of a species.

Examples: Mentha niliaca β Lamarckii (= M. longifolia × rotundifolia). The preponderance of the characters
of one or other parent may be indicated in the formulae in the following manner: Mentha longifolia > × rotundifolia,
M. longifolia × < rotundifolia. The participation of a particular variety may also be indicated, e. g. Salix caprea × daph-
noides var. pulchra.

The name × Asplenium Guichardii R. Litardière in Bull. Géogr. Bot XXI (1911), 76, for a form of the hybrid
A. foresiense × Trichomanes was incorrectly published by its author. The binary name for this hybrid group is × A. Pagesii
R. Litardière in Bull Géogr. Bot XX (1911), 204; to this name can be attached × A. Pagesii forma Guichardii.

§ 7. Names of plants of horticultural origin (Vide Appendix VII).

Art. 35. Forms and half-breeds among cultivated plants receive fancy epithets prefer-
ably in common language, as different as possible from the Latin epithets of species or varieties.
When they can be attached to a species, a subspecies, or a botanical variety, this is indicated by
a succession of names. The fancy epithet will be preceded by the letter ‘c’.

Examples: Pelargonium zonale c. Mrs. Pollock.

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Section 5. Conditions of effective publication (Art. 36).

Art. 36. Publication is effected, under these Rules, by sale to the general public
or to botanical institutions, of printed matter or indelible autographs, or by distribution of these
to specified representative botanical institutions ¹).

No other kind of publication is accepted as effective: communication of new names
at a public meeting, or the placing of names in collections or gardens open to the public, does
not constitute effective publication.

When separates from periodicals or other works placed on sale are issued in advance,
the date on the separate is accepted as the date of effective publication.

Examples. — Effective publication without printed matter: Salvia oxyodon Webb et Heldr. was published in
July 1850 in an autograph catalogue placed on sale (Webb et Heldreich, Catalogus Plantarum hispanicarum . . . ab A. Blanco
lectarum, Paris, Jul. 1850, folio). — Non-effective publication at a public meeting: Cusson announced his establishment of
the genus Physospermum in a memoir read at the Société des Sciences de Montpellier in 1770, and later in 1782 or 1783 at
the Société de Médecine de Paris, but its effective publication dates from 1787 in the Mémoires de la Société Royale de
Médecine de Paris, V, 1re partie, p. 279.

Section 6. Conditions and dates of valid publication of names

(Art. 37–45, Rec. XXI–XXIX).

Art. 37. A name of a taxonomic group is not validly published unless it is both (1)
effectively published (see Art. 36), and (2) accompanied by a description of the group or by a
reference to a previously and effectively published description of it.

Mention of a name on a ticket issued with a dried plant without a printed or auto-
graphed description does not constitute valid publication of that name.

Note. In certain circumstances a plate or figure with analyses is accepted as equivalent to a description (see
Art. 43, 44).

Examples of names not validly published. — Egeria Néraud (Bot. Voy. Freycinet. 28, 1826) published without
description or reference to a former description. — Sciadophyllum heterotrichum Decaisne et Planch. in Rev. Hortic. sér.
4, III: 107 (1854), published without description or reference to a previous description under another name. — The name
Loranthus macrosolen Steud. originally appeared without a description on the printed tickets issued about the year 1843,
with Sect. II. nn. 529, 1288 of Schimper’s herbarium specimens of Abyssinian plants; it was not validly published, however,
until A. Richard (Tent. Fl. Abyss. 1: 340, 1847) supplied a description. — Nepeta Sieheana Hausskn. was not validly published
by its appearance without a description in a set of dried plants (W. Siehe, Bot. Reise nach Cilicien, No. 521, 1896).

Art. 37 bis. A name which is not accepted by the author who published it, but is merely
proposed in anticipation of the future acceptance of the group concerned, or of a particular
circumscription, position or rank of the group (nomen provisorium) is not validly published.

Note. This Article does not apply to alternative names such as Andropogon Bequaerti De Wild., which was proposed
by De Wildeman (Bull. Gard. Bot. Brux. VI, p. 8, 1919) as an alternative name for immediate use by those who accepted the wider
circumscription of the genus Andropogon previously in use.

Examples: The generic name Conophyton Haw. — suggested by Haworth (Rev. Gen. 82, 1821) for Mesembry-
anthemum sect. Minima Haw. l. c. 81 in the following words: “If this section proves to be a genus, the name of Conophyton would
be apt” — was not validly published since Haworth did not adopt that generic name nor accept that genus: the correct name for
the genus is Conophytum N. E. Brown in Gard. Chron. Ser. 3, LXXI, p. 198 (1922).

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1) The preparation of a list of representative botanical institutions is referred to the Executive Committee
(see App. VI).

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The name Himantandra F. Muell., incidentally mentioned in remarks on Eupomatia Belgraveana F. Muell.
(Australas. Journ. Pharm., Jan. 1887; Bot. Centralbl. XXX, p. 325) — “The anther appendage is analogous to that
of Doryphora; consequently this Eupomatia might subgenerically or perhaps even generically be separated
(as Himantandra)” — is not thereby validly published: valid publication as a generic name dates from 1912, when
Diels (Engl. Jahrb., XLIX p. 164) actually adopted Himantandra and supplied a generic description.

In 1891, Baillon (Hist. Pl. X, p. 49) suggested that Tecoma spiralis Wright might perhaps represent a new
genus intermediate between Radermachera and Tecoma, or a new section. Three years later K. Schumann suggested
independently (Engl. et Prantl, Nat. Pflanzenfam. iv, Abt. 3b: 238) that Tecoma spiralis Wright might be treated as
the type of an independent genus Neurotecoma, but stated that the material available was insufficient for a thorough
investigation of the question. Neither Spirotecoma Baill. nor Neurotecoma K. Schum. was validly published by its
author. The name Spirotecoma Baill. was, however, validly published by Dalla Torre et Harms (Gen. Siphonog. 467,
n. 7734, 1904) as a generic name, with a reference to the previously published diagnoses in Engl. et Prantl, Nat.
Pflanzenfam. l.c. Cotema Britton et P. Wils. (Mem. Torr. Bot. Club 16: 107, 1920) being also based on Tecoma spiralis,
is a synonym.

Art. 38. From January 1, 1935, names of new groups of recent plants, the Bacteria
excepted, are considered as validly published only when they are accompanied by a Latin
diagnosis.

Note. This article validates the publication of names of new groups effectively published from 1908 to 1934 inclusive
with diagnoses in modern languages.

Art. 39. From January 1, 1912, the name of a new taxonomic group of fossil plants
is not considered as validly published unless it is accompanied by illustrations or figures showing
the essential characters, in addition to the description, or by a reference to a previously and
effectively published illustration or figure.

Art. 40. A name of a taxonomic group is not validly published when it is merely cited
as a synonym.

Examples. — Acosmus Desv., cited as a synonym of the generic name Aspicarpa Rich., was not validly published
thereby. — Ornithogalum undulatum Hort. Berol. ex Kunth (Enum. Pl. IV: 348, 1843), cited as a synonym under Myogalum
Boucheanum Kunth, was not validly published thereby; when transferred to Ornithogalum this species must be called Ornitho-
galum Boucheanum (Kunth) Aschers. (in Oesterr. Bot. Zeitschr. XVI: 192, 1866). — Similarly Erythrina micropteryx Poepp.
was not validly published by being cited as a synonym of Micropteryx Poeppigiana Walp. (in Linnaea XXIII: 740, 1850);
the species in question, when placed under Erythrina, must be called Erythrina Poeppigiana (Walp.) O. F. Cook (in U. S.
Dept. Agric. Bull. no. 25, p. 57, 1901).

Art. 41. A group is not characterized, and the publication of its name is not validated,
merely by mention of the subordinate groups included in it: thus the publication of the name of
an order is not validated by mention of the included families; that of a family is not validated
by mention of the included genera; that of a genus is not validated by mention of the in-
cluded species.

Examples. — The family name Rhaptopetalaceae Pierre (in Bull. Soc. Linn. Par. II: 1296, maio 1897), which was
accompanied merely by mention of constituent genera, Brazzeia, Scytopetalum and Rhaptopetalum, was not validly published,
as Pierre gave no description; the family bears the later name Scytopetalaceae Engl. (in Engl. und Prantl, Nat. Pflanzenfam.
I: 242, 1897, serius), which was accompanied by a description. — The generic name Ibidium Salisbury (in Trans.

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Hort. Soc. I: 291, 1812) was published merely with the mention of four included species: as Salisbury supplied no generic
description, the publication of Ibidium was invalid.

Art. 42. A name of a genus is not validly published unless it is accompanied (1) by
a description of the genus, or (2) by the citation of a previously and effectively published descrip-
tion of the genus under another name; or (3) by a reference to a previously and effectively
published description of the genus as a subgenus, section or other subdivision of a genus.

An exception is made for the generic names published by Linnaeus in Species Plan-
tarum, ed. 1 (1753) and ed. 2 (1762—63), which are treated as having been validly published
on those dates (see Art. 20).

Note. In certain circumstances, a plate with analyses is accepted as equivalent to a generic description
(see Art. 43).

Examples of validly published generic names: Carphalea Juss. (Gen. Pl. 198, 1789), accompanied by a generic
description; Thuspeinanta Th. Dur. (Ind. Gen. Phanerog. p. X, 1888), accompanied by a reference to the previously described
genus Tapeinanthus Boiss. (non Herb.); Aspalathoides (DC.) K. Koch (Hort. Dendrol. 242, 1853), based on a previously
described section, Anthyllis sect. Aspalathoides DC.

Art. 43. The publication of the name of a monotypic new genus of recent plants based
on a new species is validated: either (1) by the provision of a combined generic and specific
description (descriptio generico-specifica); or (2) by the provision of a plate with analyses
showing essential characters, but the latter alternative applies only to plates and generic names
published before January 1, 1908.

Examples. — The generic name Sakersia Hook. f. (Hook. Ic. Pl. Ser. III. i: 69, t. 1086, 1871) was validly publi-
shed, being accompanied by a combined generic and specific description of S. africana Hook. f. (nov. gen. et sp.) the only
known species. — The generic name Philgamia Baill. (in Grandidier. Hist. Madag. Pl., Atlas III: t. 265, 1894) was validly
published, as it appeared on a plate with analyses of P. hibbertioides Baill. (nov. gen. et sp.), published before January 1, 1908.

Art. 44. The name of a species, or of a subdivision of a species, of recent plants is not
validly published unless it is accompanied: either (1) by a description of the group or the citation
of a previously and effectively published description of the group under another name; or (2) by
a plate or figure with analyses showing essential characters but the latter alternative applies only
to plates or figures and specific or subdivisional names published before January 1, 1908.

Examples of validly published names of species. Onobrychis eubrychidea Boiss. (Fl. or. II: 546, 1872),
published with a description. — Hieracium Flahaultianum Arv.-Touv. et Gaut., published on a label with a printed
diagnosis in a set of dried plants (Hieraciotheca gallica nos. 935—942, 1903). — Cynanchum nivale Nyman (Syll. Fl.
Eur. 108, 1854—55), published with a reference to Vincetoxicum nivale Boiss. et Heldr. previously described. —
Panax nossibiensis Drake (in Grandidier, Hist. Madag. Pl., Atlas III: t. 406, 1896), published on a plate with analyses.

Examples of names of species not validly published are given under Art. 37 and 40.

Art. 45. The date of a name or of an epithet is that of its valid publication (see Art. 19,

37). For purposes of priority, however, only legitimate names and epithets published in legi-
timate combinations are taken into consideration ¹) (see Art. 60). In the absence of proof to the
contrary, the date given in the work containing the name or epithet must be regarded as correct.

On and after January 1, 1935 ²), only the date of publication of the Latin diagnosis
can be taken into account for new groups of recent plants.

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1) A legitimate name or epithet is one that is strictly in accordance with the Rules.

2) See note to Art. 38.

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For new groups of fossil plants, on and after January 1, 1912, the date is that of
the simultaneous publication of the description and figure (or if these are published at different
dates, the later of the two dates).

Examples. — Specimens of Mentha foliicoma Opiz were distributed by Opiz in 1832, but the name dates from
1882, when it was validly published by Déséglise (Menth. Op. in Bull. Soc. Études Scient. Angers 1881—82: 210); Mentha
bracteolata Opiz (Seznam 65, 1852, without description), takes effect only from 1882, when it was published with a descrip-
tion (Déséglise loc. cit. 211). — There is some reason for supposing that the first volume of Adanson’s Familles des Plantes
was published in 1762, but in the absence of certainty the date 1763 on the title-page is assumed to be correct. — Indi-
vidual parts of Willdenow’s Species Plantarum were published as follows: vol. I, 1798; vol. II. 2, 1800; vol. III. 1, 1801;
vol. III. 2, 1803; vol. III. 3, 1804; vol. IV, 2, 1806; and not in the years 1797, 1799, 1800, 1800, 1800 and 1805 respectively,
which appear on the title-pages of the volumes: it is the former series of dates which takes effect.

Botanists will do well in publishing to conform to the following recommendations:

XXI. Not to publish a new name without clearly indicating whether it is the name of a family or a tribe,
a genus or a section, a species or a variety; briefly, without expressing an opinion as to the rank of the group to which
the name is given.

Not to publish the name of a new group without indicating its type (see Recommendation IV).

XXII. To avoid publishing or mentioning in their publications unpublished names which they do not
accept, especially if the persons responsible for these names have not formally authorized their publication (see Recommen-
dation XV, e).

XXIII. When publishing names of new groups of plants, in works written in a modern language (floras,
catalogues, etc.) to publish simultaneously the Latin diagnoses of recent plants (Bacteria excepted) and the figures of
fossil plants, which will validate the publication of these names.

XXIV. In describing new groups of lower Cryptogams, especially among the Fungi or among microscopic
plants, to add to the description a figure or figures of the plants, with details of microscopic structure, as an aid to
identification.

XXV. The description of parasitic plants should always be followed by the indication of the hosts, especially
in the case of parasitic fungi. The hosts should be designated by their Latin scientific names and not by popular names in
modern languages, the significance of which is often doubtful.

XXVI. To give the etymology of new generic names, and also of new epithets when the meaning of these
is not obvious.

XXVII. To indicate precisely the date of publication of their works and that of the placing on sale or the
distribution of named and numbered plants when these are accompanied by printed diagnoses. In the case of a work
appearing in parts, the last published sheet of the volume should indicate the precise dates at which the different fascicles
or parts of the volume were published as well as the number of pages in each.

XXVIII. When works are published in periodicals, to require the publisher to indicate on the separate
copies the date (year and month, if possible the day) of publication and also the title of the periodical from which the
work is extracted.

XXIX. Separate copies should always bear the pagination of the periodical of which they form a part;
if desired they may also bear a special pagination.

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Section 7. Citation of authors’ names and of literature for purposes of precision

(Art. 46—49, Rec. XXX—XXXII).

Art. 46. For the indication of the name (unitary, binary, or ternary) of a group to be
accurate and complete, and in order that the date may be readily verified it is necessary to cite
the author who first published the name in question.

Examples: Rosaceae Juss., Rosa L., Rosa gallica L., Rosa gallica L. var. eriostyla R. Keller.

Art. 47. An alteration of the diagnostic characters or of the circumscription of
a group without exclusion of the type does not warrant the citation of an author other
than the one who first published its name.

When the changes have been considerable, an indication of their nature, and of the
author responsible for the change is added, the words: mutatis charact., or pro parte, or excl.
gen., excl. sp., excl. var., or some other abridged indication being employed.

Examples: Phyllanthus L. em. (emendavit) Müll. Arg.; Myosotis L. pro parte, R. Br.; Globularia cordifolia
L. excl. var. β (em. Lam.).

Art. 48. When a name of a taxonomic group has been proposed but not published
by one author, and is subsequently validly published and ascribed to him (or her) by another
author who supplied the description, the name of the latter author must be appended to the
citation with the connecting word ex. The same holds for names of garden origin cited
as “Hort.”.

If it is desirable or necessary to abbreviate such a citation, the name of the publishing
author, being the more important, must be retained.

Examples: Havetia flexilis Spruce ex Planch. et Triana; Capparis lasiantha R. Br. ex DC.; Gesneria Donklarii
Hort. ex Hook., or Gesneria Donklarii Hook.

Where a name and description by one author are published by another author, the
word apud is used to connect the names of the two authors, except where the name of the second
author forms part of the title of a book or periodical, in which case the connecting word in is
used instead.

Examples: Teucrium charidemi Sandwith apud Lacaita (in Cavanillesia, III: 38, 1930), the description
of the species being contributed by Sandwith and published in a paper by Lacaita. Viburnum ternatum Rehder (in
Sargent, Trees and Shrubs, II: 37, 1907) — in this latter example the second author’s name, Sargent, forms part of the
title of a book.

Art. 49. When a genus or a group of lower rank is altered in rank but retains its name
or epithet, the original author must be cited in parenthesis, followed by the name of the author
who effected the alteration. The same holds when a subdivision of a genus, a species, or a group
of lower rank, is transferred to another genus or species with or without alteration of rank.

Examples: Medicago polymorpha L. var. orbicularis L. when raised to the rank of a species becomes Medicago
orbicularis (L.) All. Anthyllis sect. Aspalathoides DC. raised to generic rank, retaining the name Aspalathoides, is cited as
Aspalathoides (DC.) K. Koch. Sorbus sect. Aria Pers., on transference to Pyrus, is cited as Pyrus sect. Aria (Pers.) DC.
Cheiranthus tristis L. transferred to the genus Matthiola becomes Matthiola tristis (L.) R. Br.

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Recommendations :

XXX. Authors’ names put after names of plants are abbreviated, unless they are very short.

For this purpose preliminary particles or letters that, strictly speaking, do not form part of the name, are sup-
pressed, and the first letters are given without any omission. If a name of one syllable is long enough to make it worth while
to abridge it, the first consonants only are given (Br. for Brown); if the name has two or more syllables, the first syllable
and the first letter of the following one are taken, or the two first when both are consonants Juss. for Jussieu, Rich. for
Richard). When it is necessary to give more of a name to avoid confusion between names beginning with the same syllables
the same system is to be followed. For instance two syllables are given together with the one or two first consonants of the
third; or one of the last characteristic consonants of the name is added (Bertol. for Bertoloni, to distinguish from Bertero;
Michx. for Michaux, to distinguish from Micheli).

Christian names or accessory designations, serving to distinguish two botanists of the same name, are abridged
in the same way (Adr. Juss. for Adrien de Jussieu, Gaertn. fil. or Gaertn. f. for Gaertner filius).

When it is a well established custom to abridge a name in another manner, it is best to conform to it (L. for
Linnaeus, DC. for De Candolle, St.-Hil. for Saint-Hilaire).

In publications destined for the general public and in titles it is preferable not to abridge.

XXXI. When citing a name published as a synonym, the words “as synonym” or pro synon. should be added
to the citation.

When an author published as a synonym a manuscript name of another author, the word ex should be used
to connect the names of the two authors.

Example: Myrtus serratus Koenig ex Steud. Nomencl. 321 (1821), pro synon., a manuscript name of Koenig’s
published by Steudel as a synonym of Eugenia laurina Willd.

XXXII. The citation of authors, earlier than the starting point of the nomenclature of a group, is indicated
when considered useful or desirable, preferably between brackets or by the use of the word ex. This method is especially
applicable in mycology when reference is made to authors earlier than Fries or Persoon.

Examples: Lupinus [Tourn. Inst. 392, t. 213, 1719] L. Sp. Pl. ed. 1: 721 (1753) and Gen. Pl. ed. 5: 332, or
Lupinus Tourn. ex L.; Boletus piperatus [Bull. Hist. Champ. Fr. 318. t. 451, f. 2, 1791—1812] Fries, Syst. Myc. 1: 388
(1821), or Boletus piperatus Bull. ex Fries.

XXXII bis. When citing in synonymy a name invalidated by an earlier homonym the citation should be followed
by the name of the author of the earlier homonym preceded by the word "non," preferably with the date of publication added.
In some instances it will be advisable to cite also any later homonym or homonyms.

Examples: Ulmus racemosa Thomas in Am. Journ. Sci. XIX (1831) 170; non Borkh. (1800). — Lindera Thunb.
Nov. Gen. III (1773) 44; non Adans. (1763). — Bartlingia Brongn. in Ann. Sci. Nat. sér. I, X (1827) 373; non Reichenb.
(1824), nec F. Muell. (1877).

XXXII ter. Misapplications of names should not be included in synonymy. Misapplied names may be
mentioned in notes appended to the synonymy but distinct from it, or to the description where there is no synonymy.

XXXII quater. In citation of literature ‘in’ should be inserted after the name of the author if the citation
refers to a periodical or other serial publication, or if it is a work by another author.

Examples: Quercus lobata Née in Anal. Ci. Nat. III (1801), 277. — Faxonanthus Greenman in Sargent, Trees
and Shrubs, I (1902), 23.

XXXII quinquies. If a name cited in synonymy applies only in part to the group under which it is cited,
it should be made clear whether the synonym includes the type, and in that case the words ‘pro parte typica’ (p.p. typ.)
should be appended; in more exact citations the parts excluded or those belonging to the group in question should be
cited, or the name of the author who changed the circumscription of the group should be added, preceded by ‘emend.’

Examples: Bradlea Adans. II (1763), 324, quoad synon. Apios Cornut (cited as a synonym of Apios Med.).
— Acer laxiflorum var. longilobium Rehd. in Sarg. Pl. Wilson. I (1911), 94, p.p. typ., excel. specim. Wilson no. 4108
(cited under A. taronense Band.-Mazz.) — Sorbus sikkimensis Wenzig in Linnaea, XXXVIII (1874), 59 quoad specim.
‘Pyrus (a) Khasia, 5000 alt.’ (cited under S. verrucosa (Dcne.) Rehd.). — Cleyera Thunb. emend. Sieb. et Zucc.
Fl. Jap. (1835) 151.

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XXXII sexies. If a generic name antedated by one of its synonyms or by a homonym is valid on
account of being a nomen conservandum, the words ‘nom. conserv.’ should be added to the citation, e.g. Protea R. Br.
in Trans. Linn. Soc. X (1810) 74, nom. conserv.; non L. (1753).

XXXII septies. When citing names in synonymy, the name or combinations of names should be cited
exactly as published by their author. If any explanatory words are required, these should be inserted in brackets.
If a name is adopted as valid with alterations from the form as originally published, it is desirable that in full
citations the exact original form should be appended.

Examples: Pyrus Calleryana Decne. (Pirus Mairei Léveillé in Fedde, Rep. XII: 189, 1913) or (P. Mairei
Léveillé in Fedde, Rep. XII: 189, 1913: ‘Pirus’). Not Pyrus Mairei. — Evonymus alata Regel, Fl. Ussur. (1861) 40,
‘alatus’ (Euonymus Loeseneri Makino in Bot. Mag. Tokyo, XXV: 229, 1911). Not Evonymus Loeseneri. — Zanthoxylum
cribrosum Spreng. Syst. I (1825) 946, ‘Xanthoxylon.’ (Xanthoxylon Caribaeum var. Floridanum A. Gray in Proc. Am.
Acad. n.s. XXIII: 225, 1888). Not Z. caribaeum var. floridanum (Nutt.) A. Gray. — Quercus bicolor Willd. (Q. Prinus
discolor Michaux, Hist. Arb. For. II: 46, 1812). Not Q. Prinus var. discolor Michaux. — Spiraea latifolia (Ait.) Borkh.
(Spiraea salicifolia γ latifolia Aiton, Hort. Kew. II: 198, 1789). Not S. salicifolia latifolia Aiton or S. salicifolia var.
latifolia Aiton. — Juniperus communis var. montana Aiton (J. communis [var.] 3. nana Loudon, Arb. Brit. IV: 2489,
1838). In this case ‘var.’ may be added in brackets, since Loudon classes this combination under ‘varieties.’ —
Ribes tricuspis Nakai in Bot. Mag. Tokyo XXX: 142, 1916, ‘tricuspe.’

Section 8. Retention of names or epithets of groups which are remodelled or divided

(Art. 50—52).

Art. 50. An alteration of the diagnostic characters, or of the circumscription of a group,
does not warrant a change in its name, except in so far as this may be necessitated (1) by trans-
ference of the group (Art. 53—55), or (2) by its union with another group of the same rank
(Art. 56—57), or (3) by a change of its rank (Art. 58).

Examples: The genus Myosotis as revised by R. Brown differs from the original genus of Linnaeus, but the
generic name has not been changed, nor is a change allowable, since the type of Myosotis L. remains in the genus. —
Various authors have united with Centaurea Jacea L. one or two species which Linnaeus had kept distinct; the group thus
constituted must be called Centaurea Jacea L. sensu ampl. or Centaurea Jacea L. em. Cosson et Germain, em. Visiani,
or em. Godron, etc.: the creation of a new name such as Centaurea vulgaris Godr. is superfluous.

Art. 51. When a genus is divided into two or more genera, the generic name must be
retained for one of them, or (if it has not been retained), must be re-established. When a parti-
cular species was originally designated as the type, the generic name must be retained for the
genus including that species. When no type was designated, a type must be chosen according
to the regulations given (Appendix I).

Examples: The genus Glycine L. Sp. Pl. ed. 1: 753 (1753) was divided by Adanson (Fam. Pl. II: 324, 327, 562,
1763) into the two genera Bradlea and Abrus; this procedure is contrary to Art. 51: the name Glycine must be kept for one
of the genera, and it is now retained for part of Glycine L. (1753). — The genus Aesculus L. contains the sections Eu-Aes-
culus, Pavia (Poir.), Macrothyrsus (Spach) and Calothyrsus (Spach), the last three of which were regarded as distinct genera
by the authors cited in parenthesis: in the event of these four sections being treated as genera, the name Aesculus must be
kept for the first of these, which includes the species Aesculus Hippocastanum L., as this species is the type of the
genus founded by Linnaeus (Sp. Pl. ed. 1: 344, 1753; Gen. Pl. ed. 5, 1754); Tournefort’s name Hippocastanum
must not be used as was done by Gaertner (Fruct. II: 135, 1791).

Art. 52. When a species is divided into two or more species, the specific epithet must
be retained for one of them, or (if it has not been retained) must be re-established. When a
particular specimen was originally designated as the type, the specific epithet must be retained

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for the species including that specimen. When no type was designated, a type must be chosen
according to the regulations given (Appendix I).

The same rule applies to subdivisions of species, for example, to a subspecies divided
into two or more subspecies, or to a variety divided into two or more varieties.

Example: Lychnis dioica L. Sp. Pl. ed. 1: 437, was divided by Philip Miller (Gard. Dict. ed. 8: nn. 3, 4, 1768)
into two species, L. dioica L. em. Mill. and L. alba Mill. — G. F. Hoffmann (Deutschlands Flora, 1800, I: 166) divided
Juncus articulatus L. (1753) into two species, J. lampocarpus Ehrh., and J. acutiflorus Ehrh. The name J. articulatus L. ought,
however, to have been retained for one of the segregate species, and has been re-established in the sense of J. lampocarpus
Ehrh. (see Briq. Prodr. Fl. Corse, I: 264, 1910). — Genista horrida DC. (Fl. franç. IV: 500, 1805) was divided by Spach
(in Ann. Sci. Nat. Bot. sér. 3, II: 253, 1844) into three species, G. horrida (Vahl) DC., G. Boissieri Spach, and G. Webbii
Spach; the name G. horrida was rightly kept for the species including the plant from Jaca in Aragon originally described
by Vahl (Symb. I: 51, 1790) as Spartium horridum. — Several species (Primula cashmiriana Munro, P. erosa Wall.) have
been separated from Primula denticulata Sm. (Exot. Bot. 109, tab. 114, 1805), but the name P. denticulata has been
rightly kept for the form which Smith described and figured under this name.

Section 9. Retention of names or epithets of groups below the rank of genus on

transference to another genus or species (Art. 53–55).

Art. 53. When a subdivision of a genus is transferred to another genus (or placed under
another generic name for the same genus) without change of rank, its subdivisional name must
be retained, or (if it has not been retained) must be re-established unless one of the following
obstacles exists: (1) that the resulting association of names has been previously published
validly for a different subdivision, or (2) that there is available an earlier and validly published
subdivisional name of the same rank.

Example: Saponaria sect. Vaccaria DC., transferred to Gypsophila, becomes Gypsophila sect. Vaccaria
(DC.) Godr.

Art. 54. When a species is transferred to another genus (or placed under
another generic name for the same genus), without change of rank, the specific epithet
must be retained or (if it has not been retained) must be re-established, unless one of
the following obstacles exists: (1) that the resulting binary name is a later homonym
(Art. 61) or a tautonym (Art. 68, 3), (2) that there is available an earlier validly published
specific epithet.

When, on transference to another genus, the specific epithet has been applied
erroneously in its new position to a different plant, the new combination must be retained
for the plant on which the epithet was originally based, and must be attributed to the author
who first published it.

Examples: Antirrhinum spurium L. (Sp. Pl. 613, 1753) when transferred to the genus Linaria, must be called
Linaria spuria (L.) Mill. (Gard. Dict. ed. 8: n. 15, 1768). — Chailletia hispida Oliv. (Fl. Trop. Afr. 1: 343, 1868) when
placed under the generic name Dichapetalum (an older name for the same genus), must be called Dichapetalum hispidum
(Oliv.) Baill. (Hist. Pl. V: 140, 1874). — Lotus siliquosus L. (Syst. ed. 10: 1178, 1759) when transferred to the genus Tetra-
gonolobus, must be called Tetragonolobus siliquosus (L.) Roth (Tent. Fl. Germ. I: 323, 1788) and not Tetragonolobus Scandalida
Scop. (Fl. Carn. ed. 2, II: 87, 1772). — Spartium biflorum Desf. (1798–1800), when transferred to the genus Cytisus by
Spach in 1849, could not be called Cytisus biflorus, because this name had been previously and validly published for a diffe-
rent species by L’Héritier in 1789; the name Cytisus Fontanesii given by Spach is therefore legitimate. — Santolina suave-
olens Pursh (1814) when transferred to the genus Matricaria must be called Matricaria matricarioides (Less.) Porter (1894);
the epithet suaveolens cannot be used in the genus Matricaria owing to the existence of Matricaria suaveolens L. (Fl. Suec.

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ed. 2: 297, 1755), an earlier validly published name. — The specific epithet of Pinus Mertensiana Bong. was transferred to
Tsuga by Carrière, who, however, erroneously applied the new combination Tsuga Mertensiana to another species of Tsuga,
namely T. heterophylla (Raf.) Sarg., as is evident from his description: the combination Tsuga Mertensiana (Bong.) must be
retained for Pinus Mertensiana Bong. when that species is placed in Tsuga; the citation in parenthesis (under Art. 49) of
the name of the original author, Bongard, indicates the type of the epithet.

Art. 55. When a variety or other subdivision of a species is transferred, without change
of rank, to another genus or species (or placed under another generic or specific name for the
same genus or species), the original subdivisional epithet must be retained or (if it has not been
retained) must be re-established, unless one of the following obstacles exists: (1) that the resulting
ternary combination has been previously and validly published for a subdivision based on a
different type, even if that subdivision is of a different rank; (2) that there is an earlier validly
published subdivisional epithet available.

When, on transference to another genus or species, the epithet of a subdivision of a species
has been applied erroneously in its new position to a different subdivision of the same rank,
the new combination must be retained for the plant on which the former combination was based,
and must be attributed to the author who first published it.

Examples: The variety micranthum Gren. et Godr. (Fl. France, I: 171, 1847) of Helianthemum italicum Pers.,
when transferred as a variety to H. penicillatum Thib., retains its varietal epithet, becoming H. penicillatum var. micranthum
Gren. et Godr.) Grosser (in Engl. Pflanzenreich, Heft 14: 115, 1903). — The variety subcarnosa Hook. fil. (Bot. Antarct.
Voy. I: 5, 1847) of Cardamine hirsuta L., when transferred as a variety to C. glacialis DC., becomes C. glacialis var. sub-
carnosa (Hook. f.) O. E. Schulz (in Engl. Bot. Jahrb. XXXII: 542, 1903); the existence of an earlier synonym of different
rank (C. propinqua Carmichael in Trans. Linn. Soc. XII: 507, 1818) does not affect the nomenclature of the variety
(see Art. 58). In each of these cases it is the earliest varietal epithet which is retained.

Section 10. Choice of names when two groups of the same rank are united,

or in Fungi with a pleomorphic life-cycle (Art. 56—57, Rec. XXXIII—XXXV).

Art. 56. When two or more groups of the same rank are united the oldest legitimate
name or (in species and their subdivisions) the oldest legitimate epithet is retained. If the names
or epithets are of the same date, the author who unites the groups has the right of choosing one
of them. The author who first adopts one of them, definitely treating another as a synonym or
referring it to a subordinate group, must be followed.

Examples: K. Schumann (in Engl. und Prantl, Nat. Pflanzenfam. III, Abt. 6: 5, 1890), uniting the three genera
Sloanea L. (1753), Echinocarpus Blume (1825) and Phoenicosperma Miq. (1865—1866) rightly adopted the oldest of these
three generic names, Sloanea L., for the resulting genus. — If the two genera Dentaria L. (Sp. Pl. ed. 1: 653, 1753, et Gen.
Pl. ed. 5: 295, no. 726, 1754) and Cardamine L. (l. c. 654, et l. c. 295, no. 727) are united, the resulting genus must be called
Cardamine because this name was chosen by Crantz (Class. Crucif. 126, 1769), who was the first to unite them. — When
H. Hallier (in Engl. Bot. Jahrb. XVIII: 123, 1893) united three species of Ipomoea, namely, I. verticillata Forsk. (1775),
I. rumicifolia Choisy (1834) and I. Perrottetii Choisy (1845), he rightly retained the name I. verticillata Forsk. for the
resulting species because verticillata is the oldest of the three specific epithets. — Robert Brown (in Tuckey, Narr. Exped.
Congo, App. V: 484, 1818) appears to have been the first to unite Waltheria americana L. (Sp. Pl. ed. 1: 673, 1753)
and W. indica L. (l. c.). Since he adopted the name Waltheria indica and stated that he considered W. americana
to be a variety of it, the name W. indica must be retained for the combined species.

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Recommendations :

XXXIII. Authors who have to choose between two generic names should note the following re-
commendations.

(1) Of two names of the same date to prefer the one which was first accompanied by the description of a species.

(2) Of two names of the same date, both accompanied by descriptions of species, to prefer the one, which,
when the author made his choice, included the larger number of species.

(3) In cases of equality from these various points of view to prefer the more correct and appropriate name.

XXXIV. When several genera are united as subgenera or sections under one generic name, the sub-
division including the type of the generic name used, may bear that name unaltered (e. g.: Anarrhinum sect. Anarrhinum;
Hemigenia sect. Hemigenia) or with a prefix (Anthriscus sect. Eu-Anthriscus) or a suffix (Stachys sect. Stachyotypus). These
prefixes or suffixes lapse when the subdivisions are raised to generic rank.

XXXV. When several species are united as subspecies or varieties under one specific name, the subdivision
which included the type of the specific epithet used may be designated either by the same epithet unaltered (e. g. Stachys
recta subsp. recta) or with a prefix (e. g. Alchemilla alpina subsp. eu-alpina), or by one of the customary epithets
(typicus, originarius, genuinus, verus, veridicus, etc.) indicating that it is the type subdivision.

Art. 57. Among Fungi with a pleomorphic life-cycle the different successive
states of the same species (anamorphoses, status) can bear only one generic and specific
name (binary), that is the earliest which has been given, starting from Fries, Systema,
or Persoon, Synopsis, to the state containing the form which it has been agreed to call the
perfect form, provided that the name is otherwise in conformity with the Rules. The
perfect state is that which ends in the ascus stage in the Ascomycetes, in the basidium in the
Basidiomycetes, in the teleutospore or its equivalent in the Uredinales, and in the spore in the
Ustilaginales.

Generic and specific names given to other states have only a temporary value. They
cannot replace a generic name already existing and applying to one or more species, any one of
which contains the “perfect” form.

The nomenclature of Fungi which have not a pleomorphic life-cycle follows the
ordinary rules.

Examples: The names Aecidium Pers., Caeoma Link, and Uredo Pers. designate different states (aecidiosporic
with or without pseudoperidium, uredosporic) in the group Uredinales: the generic name Melampsora Cast. (Obs. II: 18,
1843), applied to a genus which is defined by means of the teleutospores, cannot therefore be replaced by the name Uredo
Pers. (in Roemer, Neu. Mag. 1: 93, 1794) since the name Uredo is already used to designate a state. — Among the Dothideaceae
(Ascomycetes) a species of the genus Phyllachora Nitschke, P. Trifolii (Pers.) Fuck. (Symb. 218, 1869—70), has an older
synonym, Polythrincium Trifolii G. Kunze (Myk. Heft i: 13, t. I. f. 8, 1817), based on the conidial state of this species: the
name Polythrincium cannot displace that of Phyllachora because it represents an inferior state. — The name Phoma Fries
emend. Desm. has been given to a group of Fungi Imperfecti (Deuteromycetes), several members of which have been reco-
gnised as the spermogonial state of species of the genus Diaporthe (Valsaceae, Ascomycetes): thus Phoma Ailanthi Sacc.
belongs to Diaporthe Ailanthi Sacc., Phoma alnea (Nitschke) Sacc. to Diaporthe alnea Fuck., Phoma detrusa (Fries) Fuck.
to Diaporthe detrusa Sacc. etc. But the perfect state of many species of the “genus” Phoma is not known and in some cases
probably does not exist: hence the practical necessity for retaining the name Phoma to designate the group of Fungi Im-
perfecti in question.

Section 11. Choice of names when the rank of a group is changed (Art. 58, Rec. XXXVI).

Art. 58. When a tribe becomes a family, when a subgenus or section becomes a genus,
when a subdivision of a species becomes a species, or when the reverse of these changes takes
place, and in general when a group changes its rank, the earliest legitimate name or epithet
given to the group in its new rank is valid, unless that name or the resulting association or
combination is a later homonym (see Art. 60, 61).

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Examples: The section Campanopsis R. Br. (Prodr. Fl. Nov. Holl. 561, 1810) of the genus Campanula was first
raised to generic rank by Schrader, and as a genus must be called Wahlenbergia Schrad. (Cat. Hort. Goett., 1814), not
Campanopsis (R. Br.) O. Kuntze (Rev. Gen. II: 378, 1891). — The var. foetida L. (Sp. Pl. ed. 1: 536, 1753) of Magnolia
virginiana, when raised to specific rank, must be called Magnolia grandiflora L. (Syst. Nat. ed. 10: 1082, 1759), not Magnolia
foetida (L.) Sarg. (in Gard. and For. II: 615, 1889). — Lythrum intermedium Ledeb. (Ind. Hort. Dorp., 1822), when treated
as a variety of Lythrum Salicaria L., must be called L. Salicaria var. glabrum Ledeb. (Fl. Ross. II: 127, 1844), not
L. Salicaria var. intermedium (Ledeb.) Koehne (in Engl. Bot. Jahrb. I: 327, 1881). In all these cases the name or epithet
given to the group in its original rank is replaced by the first legitimate name or epithet given to it in its new rank.

Recommendation XXXVI. (1) When a subtribe becomes a tribe, when a tribe becomes a sub-
family, when a subfamily becomes a family, etc., or when the inverse changes occur, the root of the name should not
be altered but only the termination (-inae, -eae, -oideae, -aceae, -ineae, -ales, etc.) unless the resulting name is rejected
under Section 12 or the new name becomes a source of error or there is some other serious reason against it.

(2) When a section or a subgenus becomes a genus, or the inverse changes occur, the original name should be
retained unless it is rejected under Section 12.

(3) When a subdivision of a species becomes a species, or the inverse change occurs, the original epithet should
be retained unless the resulting combination is rejected under Section 12.

Section 12. Rejection of names (Art. 59&—69, Rec. XXXVII).

Art. 59. A name or epithet must not be rejected, changed or modified, merely because
it is badly chosen, or disagreeable, or because another is preferable or better known.

Examples: This rule was broken by the change of Staphylea to Staphylis, Tamus to Thamnos, Thamnus or
Tamnus, Mentha to Minthe, Tillaea to Tillia, Vincetoxicum to Alexitoxicum; and by the change of Orobanche rapum to
O. sarothamnophyta, O. Columbariae to O. columbarihaerens, O. Artemisiae to O. artemisiepiphyta. All these modifications
must be rejected. — Ardisia quinquegona Blume (1825) must not be changed to A. pentagona A. DC. (1834) although the
specific epithet quinquegona is a hybrid word (Latin and Greek).

Art. 60. A name must be rejected if it is illegitimate (see Art. 2). The publication
of an epithet in an illegitimate combination must not be taken into consideration for purposes
of priority (see Art. 45) except as indicated under Art. 61.

A name is illegitimate in the following cases:

(1) If it was nomenclaturally superfluous when published, i. e. if the group to
which it was applied, as circumscribed by its author, included the type of a name which
the author ought to have adopted under one or more of the Rules.

Examples: The generic name Cainito Adans. (Fam. II: 166, 1763) is illegitimate because it was a superfluous
name for Chrysophyllum L. (Sp. Pl. ed. 1: 192, 1753); the two genera had precisely the same circumscription. — The genus
Unisema Raf. (Med. Repos. N. York. V: 192, 1819) was so circumscribed as to include Pontederia cordata L., the type of
Pontederia L. (1753) . Under Art. 50 the name Pontederia L. ought to have been adopted for the genus concerned. Unisema
was therefore nomenclaturally superfluous. — Chrysophyllum sericeum Salisb. (Prodr. 138, 1796) is illegitimate, being a
superfluous name for C. Cainito L. (1753), which Salisbury cited as a synonym. — On the other hand, Cucubalus latifolius
Mill. and C. angustifolius Mill. (Gard. Dict. ed. 8: nn. 3, 4, 1768) are not illegitimate names, although these species are now
re-united with C. Behen L. (1753), from which Miller separated them: C. latifolius Mill. and C. angustifolius Mill. as
circumscribed by Miller did not include the type of C. Behen L.

(2) If it is a binary or ternary name published in contravention of Art. 16, 50, 52 or
54, i. e. if its author did not adopt the earliest legitimate epithet available for the group with its
particular circumscription, position and rank.

Example: Tetragonolobus Scandalida Scop. (1772) is an illegitimate name because Scopoli did not adopt the
earliest specific epithet available, namely siliquosus, when he transferred Lotus siliquosus L. (1759) to Tetragonolobus
(see Art. 54). On the other hand, Seseli selinoides Jacq. (Enum. Stirp. Vindob. 51: 227, 1762) is not an illegitimate

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name, although it is now treated as conspecific with Peucedanum Silaus L. (1753), Jacquin (loc. cit. 46). Jacquin did
not transfer Peucedanum Silaus to Seseli as Seseli selinoides: he described the latter as a new species, based on a cultivated
specimen of a plant found wild near Lanzendorff. As circumscribed by Jacquin, Seseli selinoides and Peucedanum Silaus
were mutually exclusive.

(3) If it is a later homonym (see Art. 61).

(4) If it is a generic name which must be rejected under Art. 67.

(5) If its specific epithet must be rejected under Art. 68.

Art. 61. A name of a taxonomic group is illegitimate and must be rejected if it
is a later homonym, that is if it duplicates a name previously and validly published for a
group of the same rank based on a different type. Even if the earlier homonym is illegi-
timate, or is generally treated as a synonym on taxonomic grounds, the later homonym must
be rejected.

When the same new name is simultaneously published for more than one group,
the first author who adopts one of them, rejecting the other, or substitutes another name for
one of them, must be followed.

Examples: The generic name Tapeinanthus Boiss. ex Benth. (1848) given to a genus of Labiatae, is a later
homonym of Tapeinanthus Herb. (1837), a name previously and validly published for a genus of Amaryllidaceae;
Tapeinanthus Boiss. ex Benth. must therefore be rejected as was done by Th. Durand (Ind. Gen. Phan. 703, 1888) who re-
named it Thuspeinanta. — The generic name Amblyanthera Müll. Arg. (1860) is a later homonym of the validly
published generic name Amblyanthera Blume (1849), and must therefore be rejected although Amblyanthera Blume is now
reduced to Osbeckia L. (1753). — Astragalus rhizanthus Boiss. (Diagn. Pl. Or., Ser. I. II: 83, 1843) is a later homonym
of the validly published name Astragalus rhizanthus Royle (Illustr. Bot. Himal. 200, 1835), and it must therefore be
rejected, as was done by Boissier who renamed it A. cariensis (Diagn. ser. I. IX: 57, 1849).

Example: Linneaus (Sp. Pl. 1753) published Aira 1 spicata on p. 63 and Aira 7 spicata on p. 64, but in ‘errata’
(vol. II, after ‘Nomina Trivialia’ and ‘Addenda,’ line 9 from base) substituted indica for spicata of species 1 on p. 63:
the name Aira spicata L. is therefore valid for species 7 on p. 64.

Note. Mere orthographic variants of the same name are treated as homonyms, when they are based on
different types — see Art. 70.

Art. 62. A name of a taxonomic group must be rejected if, owing to segregation, it is
used with different meanings, and so becomes a permanent source of confusion or error. A
list of names to be abandoned for this reason (nomina ambigua) will form Appendix IV.

Examples: The generic name Alsine L., being used by various authors for three genera of Caryophyllaceae
(Stellaria L., Spergularia J. et C. Presl, Minuartia L.), has been a permanent source of confusion and error (see Sprague
in (Kew Bull. (1920): 308). — The name Rosa villosa L. Sp. Pl. ed. 1, 491 (1753) is rejected, because it has been applied
to several different species, and has become a source of confusion. — Lavandula Spica L. Sp. Pl. ed. 1 (1753), 572
included the two species subsequently known as L. officinalis Chaix and L. latifolia Vill. The name Lavandula Spica has
been applied almost equally to these two species and, being now completely ambiguous, must be rejected (see Kew Bull.
1932: 295).

Art. 63. A name of a taxonomic group must be rejected when its application is un-
certain (nomen dubium).

Example: Ervum soloniense L. (Cent. II. Pl. 28, 1756) is a name the application of which is uncertain; it must
herefore be rejected (see Schinz und Thell. in Vierteljahrsschr. Nat. Ges. Zürich, LVIII: 71, 1913).

Recommendation XXXVII. When the correct application of a nomen dubium has been established by
subsequent investigation (of types etc.), authors adopting it should for purposes of precision cite the name of the author
who published the additional certifying evidence as well as that of the original author. The connective ‘secundum’

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(abbreviated sec.) should be used between the names of the original and certifying authors. It is also desirable to add the date
of certification.

Example: The generic name Bembix Lour. (Fl. Cochinch. 282, 1790) was a nomen dubium from the time of its
publication until 1927, when Spencer Moore (in Journ. of Bot. LXV: 279) identified it with Ancistrocladus: the latter
name has been proposed for conservation, but should the name Bembix be adopted it should be cited as Bembix Lour.
sec. Spencer Moore, 1927.

Art. 64. A name of a taxonomic group must be rejected if the characters of that group
were derived from two or more entirely discordant elements, especially if those elements were
erroneously supposed to form part of the same individual. A list of names to be abandoned for
this reason (nomina confusa) will form Appendix V.

Examples: The characters of the genus Schrebera L. (Sp. Pl. ed. 2: 1662, 1763, Gen. Pl. ed. 6: 124, 1764),
were derived from the two genera Cuscuta and Myrica (parasite and host) (see Retz. Obs. VI: 15, 1791). The characters
of the genus Actinotinus Oliv. (in Hook. Ic. Pl. t. 1740, 1888) were derived from the two genera Viburnum and Aesculus,
owing to the inflorescence of a Viburnum having been inserted into the terminal bud of an Aesculus by a native Chinese
collector. The names Schrebera and Actinotinus must therefore be abandoned.

Art. 65. A name or epithet of a taxonomic group must be rejected when it is based
on a monstrosity.

Examples: The generic name Uropedium Lindl. was based on a monstrosity which is now referred to Phragmi-
pedium cordatum Rolfe. — The name Ornithogalum fragiferum Vill. (Hist. Pl. Dauph. II: 269, 1787) was based on a mon-
strosity, and must therefore be rejected: on transference to the genus Gagea the specific epithet fragiferum must also be
rejected: the oldest name for the normal plant being Ornithogalum fistulosum Ram. ex DC. (1895), the species must be called
Gagea fistulosa (Ram. ex DC.) Ker-Gawl.

Art. 66. The name of an order, suborder, family or subfamily, tribe or subtribe, must
be changed when it is taken from the name of a genus which is known not to belong to the group
in question.

Examples: If the genus Portulaca were excluded from the family now known as Portulacaceae, the residual
group could no longer bear the name Portulacaceae and would have to be renamed. — Link (Hort. Berol. I: 230, 1827) gave
the name Tristeginae to a “suborder” of Gramineae, from Tristegis Nees (now treated as a synonym of Melinis Beauv.).
Nees (in Hooker and Arnott, Bot. Beechey’s Voy. 237, 1836) treated the group as a tribe, under the name Tristegineae.
When Stapf (in Fl. Cap. VII: 313, 1898) excluded Tristegis from the tribe Tristegeae he legitimately renamed the tribe
Arundinelleae.

Art. 67. Names of genera are illegitimate in the following special cases and must
be rejected.

(1) When they are merely words not intended as names.

(2) When they coincide with a technical term currently used in morphology unless
they were accompanied, when originally published, by specific names in accordance with the
binary method of Linnaeus. On and after Jan. 1, 1912, all new generic names coinciding with
such technical terms are unconditionally rejected.

(3) When they are unitary designations of species.

(4) When they consist of two words, unless these words were from the first combined
into one, or joined by a hyphen.

Examples: (1) Anonymos Walt. (Fl. Carol. 2, 4, 9, etc., 1788) must be rejected as being a word applied to 28
different genera by Walter to indicate that they were without names.

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(2) The generic name Radicula Hill (Brit. Herb. 264, 1756) coincides with the technical term radicula (radicle),
and when originally published, was not accompanied by specific names in accordance with the Linnean method. These
were not added until 1794 (by Moench), after the publication of the generic name Rorippa Scop. (1760). Radicula Hill
must therefore be rejected in favour of Rorippa. — Tuber Micheli ex Fries (Syst. Myc. II: 289, 1823) was accompanied by
binary specific names, e. g. Tuber cibarium, and is therefore admissible. — Names such as Radix, Caulis, Folium, Spina,
etc., can not now be validly published as new generic names.

(3) Ehrhart (Phytophylacium, 1780, and Beitr. IV: 145—150, 1789) proposed unitary names for various species
known at that time under binary names, e. g. Phaeocephalum for Schoenus fuscus, and Leptostachys for Carex leptostachys.
These names, which resemble generic names, should not be confused with them, and must be rejected, unless they have
been published as generic names by a subsequent author: for example, the name Baeothryon employed as a unitary name
of a species by Ehrhart, was subsequently published as a generic name by A. Dietrich (Sp. Pl. II: 89, 1833).

(4) The generic name Uva ursi Miller (Abridg. Gard. Dict. ed. 4, 1754) as originally published, consisted of
two separate words unconnected by a hyphen, and must therefore be rejected. On the other hand, names such as Quisqualis
(composed of two words combined into one when originally published), Sebastiano-Schaueria and Neves-Armondia (both
hyphened when originally published) are admissible.

Art. 68. Specific epithets are illegitimate in the following special cases and must
be rejected.

(1) When they are merely words not intended as names.

(2) When they are merely ordinal adjectives being used for enumeration.

(3) When they exactly repeat the generic name with or without the addition of a trans-
cribed symbol (tautonym).

(4) When they were published in works in which the Linnean system of binary nomen-
clature for species was not consistently employed.

Examples: (1) Viola “qualis” Krocker (Fl. Siles. II: 512 and 517, 1790); Atriplex “nova” Winterl (in Ind. Hort.
Bot. Univ. Pest. fol. A 8, recto et verso, 1788), the word “nova” being here used in connection with four different species
of Atriplex.

(2) Boletus vicesimus sextus, Agaricus octogesimus nonus.

(3) Linaria Linaria, Nasturtium Nasturtium-aquaticum.

(4) The name Abutilon album Hill (Brit. Herb. 49, 1756) is a descriptive phrase reduced to two words, not a
binary name in accordance with the Linnean method, and must he rejected: Hill’s other species was Abutilon flore flavo.

Linnaeus is regarded as having used binary nomenclature for species consistently from 1753 onwards, although there are
exceptions. e. g. Apocynum foliis Androsaemi, Sp. Pl. ed. 1: 213.

Art. 69. In cases foreseen in Art. 60—68 the name or epithet to be rejected is replaced
by the oldest legitimate name, or (in a combination) by the oldest legitimate epithet which will
be, in the new position, in accordance with the Rules. If none exists, a new name or epithet must
be chosen. Where a new epithet is required, an author may, if he wishes, adopt an epithet previ-
ously given to the group in an illegitimate combination, if there is no obstacle to its employment
in the new position or sense.

Examples: Linum Radiola L. (1753) when transferred to the genus Radiola must not be called Radiola Radiola
(L.) Karst., as that combination is contrary to Art. 68(3): the next oldest specific epithet is multiflorum, but the name Linum
multiflorum Lam. (1778) is illegitimate, since it was a superfluous name for Linum Radiola L.: under Radiola the

species must be called R. linoides Roth (1788), since linoides is the earliest legitimate epithet available. — The
combination Talinum polyandrum Hook. (in Bot. Mag. t. 4833, 1855) is illegitimate, being a later homonym of
T. polyandrum Ruiz et Pav. (Syst. Fl. Per. I: 115, 1798): when Bentham transferred T. polyandrum Hook. to
Calandrinia, he called it Calandrinia polyandra (Fl. Austral. I: 172, 1863). This is treated, not as a new combination,
but as a new name, C. polyandra Benth. (1863).

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Section 13. Orthography of names (Art. 70, 71, Rec. XXXVIII—XLIV).

Art. 70. The original spelling of a name or epithet must be retained, except in the case
of a typographic error, or of a clearly unintentional orthographic error. When the difference
between two generic names lies in the termination, these names must be regarded as distinct,
even though differing by one letter only. This does not apply to mere orthographic variants of
the same name.

Note 1. The words “original spelling” in this Article mean the spelling employed when the name was
validly published. They do not refer to the use of an initial capital or small letter, this being a matter of typography dealt
with by Art. 25 and 26 for names of genera and subgenera, etc. and by Rec. XLIII for specific and other epithets.

Note 2. The use of a wrong connecting vowel or vowels (or the omission of a connecting vowel in a specific
epithet, or in that of a subdivision of a species) is treated as an unintentional orthographic error which may be corrected
(see Rec. XLIV).

Note 2 bis. The liberty of correcting a name must be used with reserve, especially if the change affects the
first syllable, and above all the first letter of the name.

Note 3. In deciding whether two or more slightly different names should be treated as distinct or as ortho-
graphic variants, the essential consideration is whether they may be confused with one another or not: if there is serious
risk of confusion, they should be treated as orthographic variants. Doubtful cases should be referred to the Executive
Committee.

Note 4. Specific and other epithets of Greek origin differing merely by having Greek and Latin terminations
respectively are orthographic variants. Epithets bearing the same meaning and differing only slightly in form are considered
as orthographic variants. The genitive and adjectival forms of a personal name are, however, treated as different epithets
(e. g. Lysimachia Hemsleyana and L. Hemsleyi).

Examples of retention of original spelling: The generic names Mesembryanthemum L. (1753) and Amaranthus
(1753) were deliberately so spelt by Linnaeus and the spelling must not be altered to Mesembrianthemum and Amarantus
respectively, although these latter forms are philologically preferable. — Valantia L. (1753) and Clutia L. (1753), comme-
morating Vaillant and Cluyt respectively, must not be altered to Vaillantia and Cluytia¹): Linnaeus latinized the names of
these botanists deliberately as “Valantius” and “Clutius”. — Phoradendron Nutt. must not be altered to Phoradendrum.
— Triaspis mozambica A. Juss. must not be altered to T. mossambica, as in Engl. Pflanzenw. Ost-Afrikas C: 232 (1895). —
Alyxia ceylanica Wight must not be altered to A. zeylanica, as in Trimen, Handb. Fl. Ceylon III: 127 (1895). — Fagus
sylvatica L. must not be altered to F. silvatica. The correct classical spelling silvatica is recommended for adoption
in the case of a new name (Rec. XLII), but the mediaeval spelling sylvatica deliberately adopted by Linnaeus must
not be altered.

Example: The spelling of the generic name Lespedeza must not be altered, although it commemorates
Vicente Manuel de Céspedes (see Rhodora XXXVI: 130-132, 390-392, 1934).

Examples of typographic errors: Saurauja Willd. (1801) was a typographic error for Saurauia; Willdenow in
his herbarium always wrote the name correctly, as Saurauia. — Globba brachycarpa Baker (in Hook. f. Fl. Brit. Ind. VI:
205, 1890), and Hetaeria alba Ridley (in Journ. Linn. Soc. Bot. XXXII: 404, 1896), being typographic errors for
G. trachycarpa and H. alta respectively, should be cited as Globba trachycarpa Baker and Hetaeria alta Ridley (see Journ. of
Bot. LIX: 349, 1921). — Thevetia nereifolia A. Juss. ex Steud. is an obvious typographic error for T. neriifolia. —
Rosa Pissarti Carr. (in Rev. Hort. 1880: 314) is a typographic error for R. Pissardi (see Rev. Hort. 1881: 190).

Examples of unintentional orthographic errors: Hexagona Fries (Epicr. 496, 1836—38) was an unintentional
orthographic error for Hexagonia: Fries had previously (Syst. Myc. 1: 344, 1821) cited Hexagonia Poll. erroneously as
“Hexagona Poll.” — Libertia Laurencei Hook. f. (Fl. Tasman. II : 34, 1860) being an orthographic error for L. Lawrencei

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1) In some cases an altered spelling of a generic name is conserved; e. g. Bougainvillea (see list of nomina
conservanda proposita).

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Hook. f. (l. c. 373, t. 129), the latter spelling should be adopted: the collector’s name was Lawrence, not Laurence. — Gluta
Benghas L. (Mant. II: 293, 1771), being an orthographic error for G. renghas, should be cited as Gluta renghas L., as has
been done by Engler (in DC. Monogr. IV: 224, 1883): the vernacular name used as a specific epithet by Linnaeus is “Reng-
has” not “Benghas”. — Pereskia opuntiaeflora DC. (in Mém. Mus. Par. XVII: 76, 1828) should be cited as P. opuntiiflora DC.
(cf. also Rec. XLIV. and Art. 70, Note 2). — Cacalia napeaefolia DC. (in DC. Prodr. VI: 328, 1837) and Senecio
napeaefolius (DC.) Sch. Bip. (in Flora XXVIII: 498, 1845) should be cited as Cacalia napaeifolia DC. and Senecio napaei-
folius (DC.) Sch. Bip. respectively: the specific epithet refers to the resemblance of the leaves to those of the genus
Napaea (not Napea), and the connecting vowel “i” should have been used instead of “ae”.

Examples of different names: Rubia and Rubus, Monochaete and Monochaetum, Peponia and Peponium, Iria
and Iris, Desmostachys and Desmostachya, Symphyostemon and Symphostemon, Gerrardina and Gerardiina, Durvillea and
Urvillea, Elodes and Elodea, Peltophorus (Gramineae) and Peltophorum (Leguminosae).

Examples of different specific epithets: Senecio napaeifolius (DC.) Sch. Bip. (vide supra) and S. napifolius
MacOwan are different names, the epithets napaeifolius and napifolius being derived respectively from Napaea and Napus.

Examples of orthographic variants: — Generic names: Astrostemma and Asterostemma, Pleuripetalum and
Pleuropetalum, Columella and Columelia, both commemorating Columella, the Roman writer on agriculture, Eschweilera
and Eschweileria, Skytanthus and Scytanthus. The four generic names Bradlea Adans., Bradlaeia Neck., Bradleja Banks ex
Gaertn., Braddleya Vell., all commemorating Richard Bradley (1675—1732), must be treated as orthographic variants
because each of them has been spelt by subsequent authors both as “Bradleia” and as “Bradleya” and one only can be used
without serious risk of confusion. — Specific epithets: chinensis and sinensis; ceylanica and zeylanica; napaulensis, nepalensis,
nipalensis; polyanthemos and polyanthemus; macrostachys and macrostachyus; heteropus and heteropodus, -a, -um; poikilantha
and poikilanthes; pteroides and pteroideus; trinervis, -e and trinervius, -a, -um.

Recommendations :

XXXVIII. When a new name is derived from a Greek word containing the spiritus asper (rough
breathing), this should be transcribed as the letter h.

XXXIX. When a new name for a genus, subgenus or section is taken from the name of a person, it should
be formed in the following manner.

(a) When the name of the person ends in a vowel the letter a is added (thus Bouteloua after Boutelou; Ottoa
after Otto; Sloanea after Sloane), except when the name already ends in a, when ea is added (e. g. Collaea after Colla),

(b) When the name of the person ends in a consonant, the letters ia are added (e. g. Magnusia after Magnus,
Ramondia after Ramond), except when the name ends in er, when a is added (e. g. Kernera after Kerner).

(c) The syllables which are not modified by these endings retain their original spelling, even with the conso-
nants k and w or with groupings of vowels which were not used in classical Latin. Letters foreign to botanical Latin should
be transcribed, and diacritic signs suppressed. The Germanic ä, ö, ü become ae, oe, ue; the French é, è and ê become
generally e. In works in which diphthongs are not represented by special type, the diaeresis sign should be used
where required, e. g. Cephaëlis, not Cephaelis.

(d) Names may be accompanied by a prefix or a suffix, or modified by anagram or abbreviation. In these
cases they count as different words from the original name.

Examples: Durvillea and Urvillea; Lapeyrousea and Peyrousea; Englera, Englerastrum and Englerella; Bouchea
and Ubochea; Gerardia and Graderia; Martia and Martiusia.

XL. When a new specific or other epithet is taken from the name of a man, it should be formed in the follow-
ing manner.

(a) When the name of the person ends in a vowel, the letter i is added (thus Glazioui from Glaziou, Bureaui
from Bureau), except when the name ends in a, when e is added (thus Balansae from Balansa).

(b) When the name ends in a consonant, the letters ii are added (thus Magnusii from Magnus, Ramondii
from Ramond), except when the name ends in -er, when i is added (thus Kerneri from Kerner).

(c) The syllables which are not modified by these endings retain their original spelling, even with the con-
sonants k or w or with groupings of vowels which were not used in classical Latin. Letters foreign to botanical Latin
should be transcribed and diacritic signs suppressed. The Germanic ä, ö, ü, become ae, oe, ue, the French é, è, ê, become
generally e. The diaeresis sign should be used where required.

(d) When epithets taken from the name of a person have an adjectival form they are formed in a similar way
(e. g. Geranium Robertianum, Verbena Hasslerana).

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XLI. The same provisions apply to epithets formed from the names of women. When these have
a substantival form they are given a feminine termination (e. g. Cypripedium Hookerae, Rosa Beatricis, Scabiosa Olgae,
Omphalodes Luciliae).

XLII. New specific (or other) epithets should be written in conformity with the original spelling of the
words from which they are derived and in accordance with the rules of Latin and latinization.

Examples: silvestris (not sylvestris), sinensis (not chinensis).

XLIII. Specific (or other) epithets should be written with a small initial letter, except such as are derived
from names of persons (substantives or adjectives) or are generic or former generic names (substantives or adjectives)
in any grammatical case, or are vernacular names.

Examples: (1) Geographical epithets: Aster novi-belgii, Ficus indica, Circaea lutetiana. — (2) Personal
epithets: Phyteuma Halleri, Malva Tournefortiana. — (3) Generic names: Brassica Napus, Lythrum Hyssopifolia,
Puccinia Hieracii. — (4) Vernacular names: Schinus Molle, Astrocaryum Tucuma, Gluta Renghas.

XLIV. In the formation of specific (or other) epithets composed of two or several roots taken from Latin
or Greek, the vowel placed between the two roots becomes a connecting vowel, in Latin i, in Greek o; thus menthifolia,
salviifolia, not menthaefolia, salviaefolia. When the second root begins with a vowel and euphony requires, the connecting
vowel should be eliminated (e. g. lepidantha). The connecting vowels ae should be retained only where this is required
for etymological reasons (e. g. caricaeformis from Carica, in order to avoid confusion with cariciformis from Carex).
In certain compounds of Greek words, no connecting vowel is required, e. g. brachycarpus and glycyphyllus.

Art. 71. When the spelling of a generic name differs in Linnaeus Species Plantarum
ed. 1, and Genera Plantarum, ed. 5, the correct spelling is determined by the following regulations.

(1) If Linnaeus subsequently to 1753–54 consistently adopted one of the spellings,
that spelling is accepted, e. g. Thuja (not Thuya).

(2) If Linnaeus did not do so, then the spelling which is more correct philologically
is accepted, e. g. Agrostemma (not Agrostema).

(3) If the two spellings are equally correct philologically, and there is a great prepon-
derance of usage in favour of one of them, that one is accepted, e. g. Rhododendron (not Rhodo-
dendrum).

(4) If the two spellings are equally correct philologically and there is not a great pre-
ponderance of usage in favour of one of them, then the spelling that is in accordance or more
nearly in accordance with the Recommendations is accepted, e. g. Ludwigia (not Ludvigia),
Ortegia (not Ortega).

Section 14. Gender of generic names (Rec. XLIV bis).

XLIV bis. The gender of generic names should be determined as follows:

(1) A Greek or Latin word adopted as a generic name should retain its classical gender. In cases where the classical
gender varies the author should choose one of the alternative genders. In doubtful cases general usage should be followed.

The following names, however, whose classical gender is masculine, should be treated as feminine in accordance
with historic usage: Adonis, Orchis, Stachys, Diospyros, Strychnos; Hemerocallis (m. in Sp. Pl.: Lat. and Gr. hemerocalles, n.)
should also be treated as feminine in order to bring it into conformity with all other generic names ending in -is.

(2) Generic names which are modern compounds formed from two or more Greek or Latin words should take the
gender of the last. If the ending is altered, however, the gender should follow it.

Examples of names formed from Greek ¹) words: The generic name Andropogon L. was treated by Linnaeus as
neuter, but it, like other modern compounds in which the Greek masculine word pogon is the final element (e.g. Centropogon,
Cymbopogon, Bystropogon), should be treated as masculine. Similarly all modern compounds ending in -codon, -myces, -odon,
-panax, -stemon and other masculine words should be masculine. The generic names Dendromecon Benth., Eomecon Hance

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1) Examples of names formed from Latin words are not given as these offer few difficulties.

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and Hesperomecon E. L. Greene should be treated as feminine, because they end in the Greek feminine word mecon, poppy:
the fact that Bentham and E. L. Greene respectively ascribed the neuter gender to the names Dendromecon and Hesperomecon
is immaterial. Similarly all modern compounds ending in -achne, -carpha, -cephala, -chlamys, -daphne and other feminine
words should be feminine.

The generic names Aceras R. Br., Aegiceras Gaertn. and Xanthoceras Bunge should be treated as neuter because
they end in the Greek neuter word ceras: the fact that Robert Brown and Bunge respectively made Aceras and Xanthoceras
feminine is immaterial. Similarly all modern compounds ending in -dendron, -nema, -stigma, -stoma, and other neuter words
should be neuter. Names ending in -anthos (or -anthus), and those in -chilos (or -chilus) ought strictly speaking to be neuter,
since that is the gender of the Greek words anthos and cheilos. These names, however, have been with very few exceptions
treated as masculine, hence it is recommended to assign that gender to them. Similarly those ending in -gaster which should
strictly speaking be feminine are recommended to be treated as masculine in accordance with botanical custom.

Examples of compound generic names where the termination of the last word is altered: Hymenocarpus, Diptero-
carpus and all other modern compounds ending in the Greek masculine carpos (or carpus) should be masculine. Those in
-carpa or -carpaea, however, should be feminine, e. g. Callicarpa and Polycarpaea; and those in -carpon, -carpum or
-carpium should be neuter, e. g. Polycarpon, Ormocarpum and Pisocarpium.

(3) Arbitrarily formed generic names or vernacular names used as generic names should take the gender assigned
to them by their authors. Where the original author has failed to indicate the gender, the next subsequent author may choose
a gender and his choice should be accepted.

Examples: Taonabo Aubl. (Hist. Pl. Guiane, I: 569, 1775) should be feminine; Aublet’s two species were T. dentata
and T. punctata. — Agati Adans. (Fam. II: 326, 1763) was published without indication of gender: the feminine gender was
assigned to it by Desvaux (Journ. de Bot. I: 120, 1813), who was the first subsequent author to adopt the name, and his
choice should be accepted. Boehmer (in Ludwig, Gen. ed. 3, 436: 1760), and Adanson (Fam. II, 356, 1763), failed to
indicate the gender of Manihot: the first author to supply specific epithets was Crantz (Inst. Rei Herb. I: 167, 1766), who
proposed the name Manihot gossypifolia etc., and Manihot should therefore be treated as feminine.

Section 15. Various Recommendations (Rec. XLV—L).

XLV. When writing in modern languages botanists should use Latin scientific names or those immediately
derived from them, in preference to names of another kind or origin (popular names). They should avoid the use of the
latter unless these are very clear and in common use.

XLVI. Every friend of science should oppose the introduction into a modern language of names of plants
which are not already there, unless they are derived from Latin botanical names by means of some slight alteration.

XLVII. Only the metric system should be used in botany for reckoning weights and measures. The foot,
inch, line, pound, ounce, etc. should be rigorously excluded from scientific language.

Altitude, depth, rapidity etc. should be measured in metres. Fathoms, knots, miles etc. are terms which should
disappear from scientific language.

XLVIII. Very minute dimensions should be reckoned in μ (micromillimetres, microns, or thousandths of
a millimetre) and not in fractions of millimetres or of lines etc.; fractions encumbered with ciphers and commas easily give
rise to mistakes.

XLIX. Authors should indicate clearly and precisely the scale of the figures which they publish.

L. Temperatures should be expressed in degrees of the centigrade thermometer of Celsius.

Chapter IV. Interpretation and modification of the Rules (Art. 72, 73).

Art. 72. A small permanent International Executive Committee is established with
functions including the following:

(1) Interpreting the Rules in doubtful cases, and issuing considered “Opinions”
on the basis of the evidence submitted.

(2) Considering Nomina conservanda, Nomina ambigua, Nomina dubia, and Nomina
confusa, and making recommendations thereon to the next International Botanical Congress.

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(3) Considering all proposals for the modification of the Rules and reporting thereon
to the next Congress.

(4) Reporting on the effects of modifications of the Rules accepted at the preceding
Congress.

Art. 73. These Rules can be modified only by competent persons at an International
Botanical Congress convened for the express purpose. Modifications accepted at one Congress
remain on trial until the next Congress, at which they will receive sanction unless un-
desirable consequences, reported to the Executive Committee, show need for further amendment
or rejection.

————————

Appendix I¹). Regulation for determining types.

Appendix II. Nomina familiarum conservanda.

Appendix III. Nomina generica conservanda.

Appendix IV¹). Nomina ambigua.

Appendix V¹). Nomina confusa.

Appendix VI¹). Represententative Botanical Institutions recognized under Art. 36.

Appendix VII. Nomenclature of garden plants.

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1) Drafts of these Appendixes will be prepared for submission to the next International Congress.

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[ Appendix I was not included until the 1952, Stockholm Code ]

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Appendix II

Nomina Familiarum Conservanda

The list comprises the 185 names of families which are employed both in BENTHAM and
HOOKER’S Genera Plantarum and in ENGLER und GILG, Syllabus der Pflanzenfamilien, ed. 9/10
(1924). They are in the form prescribed by Art. 23 of the Rules (ed. 3). The name Papilionaceae
which may be used by those who regard that group as constituting an independent family, is also
included.

It has been necessary to modify the spelling of a few names in order that they may cor-
respond with the correct spelling of those of the type genera. The name Balanopsidaceae — badly
formed from Balanops — has not been altered, because no satisfactory alternative form has been
found. The numbers in parentheses following six of the family names refer to the notes at the end
of the list.

The list and the notes which follow it are reprinted from SPRAGUE, Synopsis of Proposals
concerning Nomenclature submitted to the Sixth International Botanical Congress, Amsterdam,
1935, pp. 64-66 (Cambridge, 1935). The list of 186 names was adopted by the Congress — vide
Proceedings Sixth International Botanical Congress, Amsterdam, 1935, vol. I, p. 358 (Leiden, 1936).

Cycadaceae, Gnetaceae.

Typhaceae; Pandanaceae; Najadaceae; Alismataceae; Hydrocharitaceae; Triuridaceae;
*Gramineae; Cyperaceae; *Palmae; Cyclanthaceae; Araceae; Lemnaceae; Flagellariaceae; Restio-
naceae; Centrolepidaceae; Mayacaceae; Xyridaceae; Eriocaulaceae; Rapateaceae; Bromeliaceae;
Commelinaceae; Pontederiaceae; Phylidraceae; Juncaceae; Liliaceae; Haemodoraceae; Amarylli-
daceae; Taccaceae; Dioscoreaceae; Iridaceae; Burmanniaceae; Orchidaceae.

Casuarinaceae; Piperaceae; Chloranthaceae; Salicaceae; Myricaceae; Balanopsidaceae;
Leitneriaceae; Juglandaceae; Batidaceae; Urticaceae; Proteaceae; Santalaceae; Olacaceae; Lor-
anthaceae; Balanophoraceae; Aristolochiaceae; Polygonaceae; Chenopodiaceae; Amaranthaceae
(1); Nyctaginaceae; Phytolaccaceae; Portulacaceae; Caryophyllaceae.

Nymphaeaceae; Ceratophyllaceae; Ranunculaceae; Berberidaceae; Menispermaceae;
Magnoliaceae; Calycanthaceae; Annonaceae (2); Myristicaceae; Monimiaceae; Lauraceae; Papa-
veraceae; Capparidaceae; *Cruciferae; Resedaceae; Moringaceae.

Sarraceniaceae; Nepenthaceae; Droseraceae; Podostemaceae (3); Crassulaceae; Saxi-
fragaceae; Pittosporaceae; Bruniaceae; Hamamelidaceae; Platanaceae; Rosaceae; Connaraceae;
*Leguminosae; †Papilionaceae.

Geraniaceae; Linaceae; Humiriaceae (4); Zygophyllaceae; Rutaceae; Simaroubaceae;
Burseraceae; Meliaceae; Malpighiaceae; Vochysiaceae; Tremandraceae; Polygalaceae; Euphor-
biaceae; Empetraceae; Coriariaceae; Anacardiaceae; Cyrillaceae; Celastraceae; Salvadoraceae;
Stackhousiaceae; Sapindaceae; Sabiaceae; Rhamnaceae; Chlaenaceae; Tiliaceae; Malvaceae;
Sterculiaceae.

————————————————————————————————————————————————————————————————————

* An alternative name ending in -aceae may be used for this family.

† If treated as an independent family.

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Dilleniaceae; Ochnaceae; *Guttiferae; Dipterocarpaceae; Elatinaceae; Frankeniaceae;
Tamaricaceae; Cistaceae; Bixaceae; Lacistemaceae; Canellaceae; Violaceae; Turneraceae; Passi-
floraceae; Loasaceae; Datiscaceae; Begoniaceae; Cactaceae; Penaeaceae; Thymelaeaceae; Elae-
agnaceae; Lythraceae; Rhizophoraceae; Combretaceae; Myrtaceae; Melastomataceae; Haloraga-
ceae (5); Araliaceae; *Umbelliferae; Cornaceae.

Diapensiaceae; Ericaceae; Epacridaceae; Myrsinaceae; Primulaceae; Plumbaginaceae;
Sapotaceae; Ebenaceae; Styracaceae.

Oleaceae; Loganiaceae; Gentianaceae; Apocynaceae; Asclepiadaceae; Convolvulaceae;
Polemoniaceae; Lennoaceae; Hydrophyllaceae; Boraginaceae (6); Verbenaceae; *Labiatae; Sola-
naceae; Scrophulariaceae; Bignoniaceae; Pedaliaceae; Orobanchaceae; Gesneriaceae; Columel-
liaceae; Lentibulariaceae; Acanthaceae; Myoporaceae; Plantaginaceae.

Rubiaceae; Caprifoliaceae; Valerianaceae; Dipsacaceae; Cucurbitaceae; Campanulaceae;
Goodeniaceae; Stylidiaceae; Calyceraceae; *Compositae.

Notes:

(1) Amaranthaceae. — The name of the type genus is Amaranthus L. (1753). This spelling
must be retained under International Rules, since it was deliberately adopted by LINNAEUS in preference
to the classical form Amarantus (see Kew Bull. 1928: 287, 343). The family name is therefore Amar-
anthaceae (not Amarantaceae).

(2) Annonaceae. — The name of the type genus is Annona L. (1753), which was deliberately
adopted by LINNAEUS in preference to Anona. He rejected the latter on the ground that it was a barbarous
name (see Kew Bull. 1928 :344). The family name is therefore Annonaceae.

(3) Podostemaceae. — The name of the type genus is Podostemon. The family name is there-
fore Podostemaceae (see Kew Bull. 1933: 46).

(4) Humiriaceae. — The correct name for the type genus is Houmiri Aubl. (1775). The Latin-
ized form Humiria Jaume St. Hil. (1805) is so widely employed, however, that it seems desirable to con-
serve it. Unless this is done, the spelling of the family name will have to be altered.

(5) Haloragaceae. — The name of the type genus is Haloragis (see Kew Bull. 1928: 354).
The International Rules prohibit alterations in spelling based solely on philological grounds. The spelling
of the family name follows that of the generic one.

(6) Boraginaceae. — It has been shown that the correct spelling, under International Rules, of
the name of the type genus is Borago (see Kew Bull. 1928: 288, 348). The name of the family must cor-
respond.

* An alternative name ending in -aceae may be used for this family.

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                 [ Appendix III, on conserved names of genera, is not included here.

                      Appendix IV to VI did not exist at this point, and, in fact, were never realized
                      A draft list for Appendix VI was submitted at the 1935 Amsterdam Congress,
                      but only for discussion by the Executive Committee.

                      An Appendix on the nomenclature of fossil plants was approved at Amsterdam. ]

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Appendix VII.

Nomenclature of Garden Plants.

–—–

                 At the International Horticultural Conference of London in 1930 the nomenclature
of Garden Plants was discussed. The principles and rules governing the naming of plants
by botanists were accepted as governing the naming of plants of garden origin. Names of species
and botanical varieties are thus fully provided for. Plants raised in gardens as seedlings or sports
of these species or as hybrids between species have often to be named by non-botanical workers
and the following “rules” were framed for their guidance.
a) The name of a horticultural “variety” should be placed after that of the species to which
      it belongs and its status should in general be indicated by the contraction “var.”
b) The varietal name should be of Latin form only when it expresses some character of the
      plant, e. g. nanus, albus, fastigiatus, or its place of origin, e. g. kewensis.
c) The name will thus usually be a “fancy” name beginning with a capital letter, e. g. Galega
      officinalis var. George Hartland (not Galega officinalis var. Hartlandii); Dianthus deltoides var.
      Brilliant; Pea “Masterpiece”. These names do not form combinations with the binary name
      and if the name of their raiser or author is cited it remains the same even if the preceding
      part of the name is changed; e. g. Lilac “Decaisne” Lemoine, Syringa vulgaris “Decaisne”
      Lemoine.
d) Varietal names must not be translated when transferred from other languages, but must be
      preserved in the language in which they were originally described. Where desirable a trans-
      lation may be placed in brackets after the varietal name.
e) So far as possible names of horticultural varieties should consist of a single word; the use
      of not more than three words is permitted as a maximum.
      1. A varietal name in use for one variety of a kind of plant should not be used for another
           variety of that kind, even though it may be attached to a different species.
           Thus the use of the name Narcissus Pseudonarcissus “Victoria” should preclude the use
           of “Victoria” as a varietal name for any other species of Narcissus, such as Narcissus
           poeticus “Victoria”. Similarly there should be but one Iris “Bridesmaid”, one Plum
           “Superb” and so on.
      2. Varietal names likely to be confused with one another should be avoided. For instance,
           the use of the name “Alexander” should preclude the use of “Alexandra”, “Alexandria”
           and “Alexandrina” as varietal names for the same kind of plant.
      3. Where personal names are used to designate varieties, the prefix “Mr., Mrs., Miss”,
           and their equivalents should be avoided.

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      4. Excessively long words and words difficult to pronounce should be avoided.
      5. The articles “a” and “the” and their equivalents should be avoided in all languages when
           they do not form an integral part of the substantive. For instance “Colonel”, not “the
           Colonel” ; “Giant”, not “the Giant”; “Bride”, not “the Bride”.
      6. Existing names in common use should not be altered to conform to these rules, but atten~
           tion should be paid to them in all new names proposed.
f) The names of horticultural hybrids are formed as provided in the International Rules of
      Botanical Nomenclature. If a Latin name has been given to a hybrid form of uncertain origin
      which cannot be referred to a Latin binominal it must be treated like a vernacular (fancy)
      name; e. g. Rhododendron “Atrosanguineum”, Rhododendron “Purpureum grandiflorum”.
g) All plants raised by crossing the same two species receive the same “specific” name, variations
      between the seedlings being indicated where necessary by varietal names framed as already
      described (a-e). In practice in crossbred plants the specific name is frequently omitted;
      e. g. Iris “Ambassadeur”.
h) Publication. In order to be valid a name must be published.
      1. The publication of a name of a horticultural variety or hybrid is effected by a recognizable
           description, with or without a figure, in any language written in Roman characters.
      2. The description must appear in a recognized horticultural or botanical periodical, or in
           a monograph or other scientific publication, or in a dated horticultural catalogue.
      3. The mention of a variety without description in a catalogue or in the report of an exhibition
           is not valid publication, even when a figure is given. It is desirable that descriptions of
           new varieties in horticultural catalogues should also be published in periodical horti-
           cultural papers.
                The Committee also arranged for the preparation of a list of generic names to be
recommended for use in catalogues etc. In regard to taxonomic differences the names recommen-
ded would be selected with reference to recent monographs and prevailing usage in modern
botanical and horticultural literature but avoiding extremes in splitting and lumping.

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[ Not present in this edition ]

[ sic ]

[ supposed to be superscript ]