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EEVISTON OF THE BRITISH WILLOWS. 397 



very abundant, are softer, duller-coloured, longer, more slender 

 and less rigid, and (always ?) unicolorously whitish. 



As regards the twigs, the youngest — in both forms— are some- 

 what pubescent, but more constantly and decidedly in Salts 

 nigricans than in S. phylicifolia ; and whilst in the latter they are 

 soon glabrous and shining, in the former they frequently remain 

 downy and dull. 



In the organs of fructification there seem to be no sufficiently 

 constant differences. 



4 



But, as already mentioned, there are a considerable number of 

 examples which, show a greater or less combination of the charac- 

 ters just described. In some the affinity with S. phylicifolia is 

 exhibited by the more slender, brighter-coloured, and glabrous 

 twigs; in others it is these parts only which retain the resemblance 

 to 8. nigricans. In intermediate forms the twigs are usually more 

 phylicifolia-like, the leaves thick and firm, shining above, but less 

 brightly green than iu phylicifolia, somewhat, but not very, 

 pubescent below, and with the shining and coloured hairs of 



phylicifolia mingled with the duller aud softer pubescence of 

 nigricans. 



Wimmer and others have considered these forms to be hybrids 

 between phylicifolia and nigricans, and have distinguished them 

 by the name of 8. phylicifolia-nigricans, Wimm. It may be 

 that Wimmer's views are correct, and that these are really hybrid 

 forms. I am inclined, however, to think that they are only the 

 intermediate conditions of one species ; and if this is the case one 

 name only— & phylicifolia— must be retained, to the exclusion of 



.' ni 9 ri cans and 8. phylicifolia-nigricans even as varieties. But 

 since the general concensus of opinion seems to be in favour of 

 keeping nigricans as a form distinct from phylicifolia, it will be 

 expedient, in the meantime, to distinguish by "Wimmer's name, 



hough not in his sense, the intermediate forms, and to use 

 the designation 8. phylicifolia-nigricans for those examples 

 which show a combination of the characters of phylicifolia and 

 nigricans. 



Having thus indicated the characteristics of the three forms 

 Which I have united under & phylicifolia, some of the British 

 varieties which were ascribed to each when they were treated as 

 distinct species must be noticed. 



Oi both 8. phylicifolia and 8. nigricans a considerable number 

 named forms—once supposed to be distinct species — are 



LDrN - J °UaN.— BOTANY, VOL. XXVII. 2 E 







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