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REVISION OF THE BRITISH WILLOWS. 379 





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Desf., which is connected with Salix silesiaca by S. grandifolia, 

 and has so much affinity with these that it might be considered to 

 be a southern modification of one of them. S.pedicellata forms the 

 connecting link with S. canariensis, C. Sm., a species very similar to 

 it, restricted to some of the North-Atlantic islands. Besides these, 

 certain subspecies of S. cinerea occur in Russia and in Persia. 



From these instances it would seem that there is a tendency in 

 S. cinerea aud S. Gaprea to develop local races, some of which are 

 so sufficiently distinct as to be considered as species. Hence it 

 would not be very surprising if in Britain an insular form should 

 occur, and the differences between it and the Continental plant 

 become greater by separation, since, on account of the absence 

 of economic value in the species and its great abundance, living 

 plants from the Continent would not likely be commonly, if at all, 

 brought to this country. 



In such closely allied Willows as the Caprece the characteristic 

 distinctions are more easily seen than described. It is thus 

 rather difficult to put in words the differences between the Conti- 

 nental and the British cinerea, though the facies is sufficiently 

 noticeable. 



In the first place, the European plant has, as the name implies, 

 au aa hy-g*ey appearance, which is, in great measure, absent from 

 the British form. This ashy-grey colour is owing to the pubes- 

 cence of the twigs (« veluti incani," Wimmer; " griseo-tomentosi " 

 and "incani," Andersson ; cano-tomentosi," Koch] "grisatre- 

 tomenteux," Grenier) and of the underside of the leaves (" grisea," 

 cinerea," u de couleur cendree "), and sometimes of the upper 

 surf ace also. The British plant is, as regards the great majority 



specimens, much less pubescent. The pubescence of the twigs 

 18 ' mor eover, not of a hoary-grey colour (except, perhaps, in the 

 youngest shoots), but inclining rather to fuscous black; and the 

 pubescence of the underside of the leaves has most usually a more 

 °r less considerable admixture of shining, rust-coloured, short, 

 cnsped hairs, which, with scarcely an exception (one will be 

 noted), none of the Continental specimens show nor do the Conti- 

 nental descriptions mention. 



In the second place, the average size of the leaves seems to be 

 ess in the British than in the Continental plant. 



-rroin this difference in the nature of the pubescence and in the 

 »ize of the leaves, it follows that the British S. cinerea is more 

 remote from 8. Caprea than the Continental form, and rather 

 bearer to S. aurita. 





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