432 A TEXT-BOOK OF BOTANY. 



names are to be in Latin for all groups. When taken from another 

 language, a Latin termination is given them, except in cases 

 sanctioned by custom. If translated into a modern language, it is 

 desirable that they should preserve as great a resemblance as 

 possible to the original Latin names. 



Among the rules to be followed in designating the nature and 

 the subordination of the several groups, the following were 

 adopted : 



Every individual plant 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). In a number of species varie- 

 ties and forms are also distinguished. In some cultivated species 

 there are unlimited modifications. The crossing of one species 

 \vith another species gives rise to a hybrid. 



Regarding the point of nomenclature and limitation of principle 

 of priority, it was agreed at the congress that botanical nomen- 

 clature should begin with the Species Plantarum of Linnaeus, 

 ed. i (1753), for all groups of vascular plants. It was further 

 agreed to associate genera, the names of which appear in this 

 work, with descriptions given of them by him in his Genera Plan- 

 tarum, ed. 5 (1754). 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 1753, 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. 



Among the recommendations, the following suggestions were 

 made in regard to the nomenclature of divisions, classes, families, 

 genera, and species : 



i. Names of divisions and subdivisions, of classes and sub- 

 classes are taken from one of their characters. They are expressed 

 by words of Greek or Latin origin, some similarity of form and 

 termination being given to those that designate groups of the same 

 nature, as Angiospermse, Gymnospermse ; Monocotyledoneae, Di- 

 cotyledoneae ; Coni ferae; Pteridophyta. Among Cryptogams old 



