199 37 



Art. 14. The fertilization of one species by another. gives rise to a hybrid 

 (hybrida): that of a modification or subdivision of a species by another modification 

 of the same species gives rise to a haif-breed {mistus, mule of florists). 



Recommendations. 



I. Till' arranni'iiieiit of species in a genus or in a subdivision of a geniis is niaile liy means 

 of typographie signs, letters or nunierals. Hybrids are arranged after one of the parent s]iecies, with 

 the sign x placed before tlie generic name. 



The arrangement of subspecies under a species is made by letters or nunierals; tliat of 

 varieties by the séries of greelv letters a, ß, y, etc. Croups below varieties and also half-breeds are 

 indicated liy letters, nunierals or tyjjograiihic signs at the author's will. 



Modifications of cultivated plants sliould be associated, as far as possible, with the sjiecies 

 froni which they ai'e derived. 



Ciiai)ter III. On the maiiner of designating each group 

 or association of plants. 



Section 1. General principles; priority. 



Art. 15. Each natural group of phints') can bear in science only one valid 

 désignation, nainely the oidest, provided that it is in conformity witii the ruies of 

 Nomenclature and the conditions laid down in articles 19 and 20 of section 2. 



Art. 16. The désignation 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 niay 

 be understood \vhen we wish to speak of it. 



Art. 17. No one should change a name or a conibination of names without 

 serions motives, based on a more profound knowledge of facts, or on the necessity 

 of giving up a nomenclature that is contrary to rules. 



Art. IS. The form, nuniber and arrangement of names dépend on the nature 

 of each group, according to the following rules. 



Section 2. Point of departure for nomenclature; limitation of principle of priority. 



Art. 19. Botanical nomenclature begins witli the Sprcics Plantantm of 

 Linnaeus, éd. 1. (1753) for ail groups of vascular plants. It is agreed to associate 

 geneia, the names of which appear in this work, with the descriptions given of them 

 in the Genera Plaiitanim éd. ô. (1704). 



Art. 20. However, to avoid disadvantageous changes in the nomenclature 

 of gênera by the strict application of the rules of Nomenclature, and especially of the 

 principle of i)riority in starting from 17ô3, the rules provide a list of names which 

 must be retained in ail cases. These names are by préférence those which hâve come 

 into gênerai use in the fifty years following their publication, or which hâve been 

 used in monographs and important lioristic (floristiques) works uji to the year 1890. 

 The list of thèse names forms an appendix to the ruies of Nomenclature. 



1) See observation to article U. 



