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DT*. F. BUCHANAN WHITE S 



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sible that the plants known as Salix fragilis and 8. alba may be 

 only extreme states of one species, and that S. viridis is the inter- 

 mediate condition. In favour of this view may be cited Hartig s 

 statement that in N.W. Germany, where 8. fragilis is very rare 

 8. viridis is very abundant, and Kerner's that in Lower Austria 

 it is scarcely less common than 8. fragilis itself. 



The question of the specific identity of 8. fragilis and 8. alba 

 is one, however, that must be studied in the supposed metropolis 

 of the species in Asia, where it can alone be determined 

 whether the connecting forms mentioned by Andersson are inter- 

 mediates or hybrids. In Western Europe, into which they have 

 immigrated or been brought, they must, in the meantime, be 

 treated as distinct species and 8. viridis as a hybrid between 

 them. 



In its most intermediate or typical condition S. viridis (or at 

 least the $ plant) is not difficult to recognize, but those states 

 (especially of the c?) which approach one or other of the parents 

 are by no means easy of determination. 



Compared with S. fragilis, typical S. viridis has leaves of a 

 darker green *, rather less shining, more finely serrated on the 

 margin, and less oblique towards the apex ; the 8 catkins rather 

 dense-flowered, narrower and longer ; the ? catkins more (usually) 

 erect and more slender; capsules smaller, paler when dried, 

 conical-cylindrical, contracted into the style, and hence more or 

 less obtuse at the apex (instead of lanceolate-subulate or ovate- 

 lanceolate, attenuate into the style), and with a shorter pedicel 

 not exceeding twice the length of the nectary (instead of 2-3 

 times as long f). 



From 8. alba, S. viridis differs by the broader and larger leaves, 

 very soon quite glabrous, and more shining above; longer and 

 less dense-flowered cf catkins ; and larger, usually more distinctly 

 pedicelled and distinctly styled capsules. The capsules hold an 

 intermediate place in size between those of fragilis and of alba. 

 Tak WQ the average of fragilis capsules as 7 mm. in length, and 

 of alba as 2 mm., those of viridis are about 5 mm. 



The habit of the tree is also different from that of both its 



* In his directions to the artist, noted on the original drawing for Eng. Bot., 

 Smith says, regarding Russelliana, " green of every part lighter than in S. 

 fragilis (i. e. his fragilis, which is viridis), and also " the midrib is much broader 

 in this than in Jragilis.- 9 



1 t The pedicel of fragilis, whilst usually 2-3 times the length of the necfc 

 is sometimes barely twice the length, but varies in the same catkin. 



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