62 THE BRITISH WILLOWS 



leaves are thicker and of a firmer texture, of a brighter and more 

 shining green on the upper surface and often more glaucous 

 below ; whilst in S. nigricans they are thinner, less compact in 

 substance, of a duller green and less shining above, and usually 

 less brightly glaucous below. . . . S. nigricans has also a 

 greater tendency to turn black in drying, but this is by no means 

 invariable, &c." He adds that S. phylicifolia is less pubescent 

 (sometimes glabrous), and soon glabrescent ; and that the hairs 

 are shorter and straighter, somewhat shining, and have some red- 

 brown ones intermixed. In S. nigricans the hairs are more 

 plentiful, softer, duller white, longer and less rigid. The young 

 branches of the former are soon glabrous, and turn a shining 

 brown ; of the latter, more persistently pubescent and remaining 

 dull. 



In spite of these differences, Dr. B. White, influenced by the 

 existence of many intermediate forms connecting the two, com- 

 bined them as one species ; and placed S. nigricans as a variety 

 under S. 'phylicifolia, as Linnaeus had previously left it. 



Wimmer added another distinguishing character, affecting the 

 $ flowers, describing the filaments of S. nigricans as pilose, 

 and those of S. phylicifolia as glabrous. And regarding each as a 

 true species, he placed some of the intermediate forms as hybrids, 

 under the name S. phylicifolia-nigricans, which he afterwards 

 altered to S. nigricans-Weigeliana (Denkschr. Schles. Ges. 168; 

 Sal. Eur. 217). 



S. J. Enander reduces the limits of the types of the two species 

 still more, describing the leaves of S. phylicifolia as normally 

 glabrous with the tip entire or free from serration, and the ovaries 

 always pubescent ; and S. nigricans as having the pubescent 

 leaves serrate to the tip, and the ovaries always glabrous. All 

 apparent forms of these two species, which confuse these characters 

 and do not conform to their restricted type, are regarded by him 

 as hybrids between the two (or between one of them and some 

 other species). 



There is much to be said for this drastic method of clearing 

 up a difficult question (see the Introduction to Enander's Sal. 

 Scand. exs. fasc. iii.). 



The name which the species should bear now requires con- 

 sideration. Linnaeus, after describing his S. phylicifolia, separated 

 some form of what has since been known as S. nigricans under 

 the denomination of S. phylicifolia f3. Smith took in hand what 

 he thought to be this form, combining $ specimens from this 

 country with $ specimens from Lapland for the purpose, and 

 described this combination as S. nigricans (Engl. Fl. iv. 172). 

 The name has very generally been accepted, in spite of obvious 

 objections, arising to begin with from Smith's own account ; first, 

 the assumption that the <? British specimens were the same 

 species and form as the ? specimens from Lapland (which was 

 not the case) ; secondly, the distribution he assigns to S. nigricans 

 in Britain (Engl. Fl. I.e.), "in fens, osier-grounds, woods, and 

 thickets," which at once suggests some mistake; while the two 



