R e com men d a tio n s .
I. The arrangement of species in a genus or in a subdivision of a genus is made by means
of typographic signs, letters or numerals. Hybrids are arranged after one of the parent species, with
the sign x placed before the generic name.
The arrangement of subspecies under a species is made by letters or numerals; that of
varieties by tlie series of greek letters a, /?, y, etc. Groups below varieties and also half-breeds are
indicated by letters, numerals or typographic signs at the author’s will.
Modifications of cultivated plants should be associated, as far as possible, with the species
from which they are derived.
Ib'8. In the case of parasites, especially parasitic fungi, authors who do not give specific
value to forms characterized from a biological standpoint hut scarcely or not at all from a morphological
standpoint, should distinguish within the species special forms {fo rm a specialis, f . sp.) characterized
by their adaptation to different hosts.
Chapter III. On th e ma ime r of d e s ig n a tin g ea ch g ro u p
o r a s so c ia tio n of p lan ts.
S e c tio n 1. General principles; priority.
Art. 15. Eacli natural group of plants) can bear in science only one valid
designation, namely the oldest, provided that it is in conformity with the rules of
nomenclature and the conditions laid down in articles 19 and 20 of section 2.
Art. 16. The designation of a group by one or several names is not for
the purpose of describing the characters or the history of the group, but that we
may be understood when we wish to speak of it.
Art. 17. No one should change a name or a combination of names without
serious motives, based on a more profound knowledge of facts, or on the necessity
of giving up a nomenclature that is contrary to rules.
Art. 18. The form, number and arrangement of names depend on the nature
of each group, according to the following rules.
S e c tio n 2. Point o f departure for nomenclature; limitation o f principle o f priority.
Art. 19. Botanical nomenclature begins for the different groups of plants
(recent and fossil) at the following dates ^).
Cl) Phanerogamae und Pteridophyta, 1753 (Linnaeus, Species Plantarum,
ed. 1).
b) Muscineae, 1801 (Hedwig, Species Muscorum).
c) Sphagnaceae and Hepaticae, 1753 (Linnaeus, Species Plantarum, ed. 1).
d) Lichenes, 1753 (Linnaeus, Species Plantarum, ed. 1).
e) Fungi: Uredinales, Ustilaginales and Gasteromycetes, 1801 (Persoon,
methodica Pungorum).
f ) Fungi caeteri, 1821—32 (Fries, Systema mycologicum).
1) The starting points of the nomenclature of the following groups are reserved for
th e consideration of the Congress at London, 1915. Schizomycetes (Bacteria), Schizophyceae (excl.
Nostocaceae), Flagellatae (incl. Dinoflagellatae), Bacillariaceae (Diatomaceae).
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g) Algae, 1753 (Linnaeus, Species Plantarum, ed. 1). Exceptions: Nostocaceae
homocysteae, 1891—93 (Gomont, Nostocaceae homocysteae)', Nostocaceae heterocysteae,
1886 (Bornet et Flahault, Nostocaceae heterocysteae)', Desmidiaceae, 1848
(Ralfs, British Desmidiaceae)', Oedogoniaceae, 1900 (Hirn, Monographie und Ikono-
graphie der Oedogoniaceen).
h) Myxomycètes, 1753.
I t is agreed to associate genera, the names of which appear in Linnaeus’s
Species Plantarum, ed. 1., with the descriptions given of them in the Genera
Plantarum, ed. 5. (1754).
Art. 20. 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. 19, the rules provide a
list of names which must be retained in all cases. 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.
For the guidance of palaeobotanists a double list is provided: 1® a list of
generic names of recent plants, duly published and generally admitted, which coincide
with older generic names in palaeobotany; 2® a list of generic names of fossil plants,
duly published and generally admitted, which coincide with older homonyms of recent
plants which have lapsed into synonymy, in order to prevent the latter being used
again. The lists form an appendix to the rules of nomenclature^).
S e c tio n 3. Nomenclature o f the different kinds o f groups.
§ 1. Names o f groups above the family.
Recommendations^ The following suggestions as to the nomenclature of groups of higher
rank than the family will tend to clearness and uniformity.
I I . Names of divisions and subdivisions, of classes and subclasses are taken from one of
tbeir chief characters. They are expressed by words of greek or latin origin, 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.
I I I . Orders are designated preferably by 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 retained 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, Centrospermae, Pariétales, Tubiflorae, Microspermae, Contortae. Examples of names of
suborders: Bromeliineae (from Bromeliaceae), Malvineae (from Malvaceae), Tricoccae, Enantioblastae.
§ 2. Names o f families and subfamilies, tribes and subtribes.
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Art. 21. Families (familiae) are designated by the name of one of their
genera or ancient generic names with the ending -aceae.
1) The elaboration of this double list has been reserved for the Congress of 1915.
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