THE BRITISH WILLOWS 87 



THE DESIGNATION OF HYBRID WILLOWS. 



In this paper hybrids are usually designated by the names 

 of the parent species with a x between them, and the alphabetic 

 order was adopted from the first, with two exceptions. A third 

 exception arose in the course of the work through a change in the 

 name of a species. 



1. Since the Synandrce are distinguished by the connation of 

 the filaments from all others which have the filaments free, the 

 hybrids of S. purpurea, which all partake of this peculiarity in a 

 greater or less degree, are kept in one group with S. purpurea, 

 instead of being dispersed in observance of the alphabetic rule. 



2. x\nother group of hybrids are kept together on account of 

 their close alliance and general resemblance, viz., those of S. vimi- 

 nalis with the three British species of Gaprece. The difficulty of 

 distinguishing these according to their parentage was evaded by 

 Andersson, in whose account (DC. Prodr. xvi. (2), 264-268) they 

 are placed below S. viminalis, thus : — 



X >S'. stipularis Sm. 



ft vestita. 



XX S. Smithiana Willd. 



a sericans (Tauschj. 

 var. latifolia. 

 var. angustifolia. 

 var. subobscura. 

 ft velutina Schrad. 



var. ferruginea (Forbes), 

 y acuminata Sm. (S. caprea-dasy dados Wimmer ; 

 S. Galodendron Wimmer). 

 B. White (Revision, 414) states and criticizes this arrangement, 

 remarking that if S. caprea, S. cinerea, and S. aurita are retained 

 as distinct species, their several combinations should have separate 

 recognition. But on account of the " almost insurmountable 

 difficulty of distinguishing between them," he decided to adopt a 

 slight modification of Andersson's arrangement. 



Recognizing that the hybrids of S. viminalis with S. aurita, 

 S. caprea, and S. cinerea are very closely allied and not always 

 easily distinguished, I have given them a position under Viminales, 

 and grouped with them S. stipularis Sm. and S. acuminata Sm., 

 which have been suspected of having a similar though unascer- 

 tained origin. This is practically Wimmer 's method (Sal. Eur. 

 174-190), who, however, imposed a fresh name (S. Galodendron) 

 on S. acuminata, and added S. holosericea Willd., $, as a separate 

 member of the group. 



3. Another breach of the rule of alphabetic order occurs in the 

 hybrids of the same three species of the Gaprece with S. Ander- 

 soniana (S. nigricans) Sm. The descriptions of these were in 

 type and in position before it was finally decided to pass over 



