INTRODUCTION. 



The purpose of this paper is to make the willows of Ohio 

 knowable to persons of moderate skill in the determination of 

 plants. Perhaps it would be too much even to hope that it will 

 enable beginners in Botany to deal with the willows. But if it 

 helps those who have already some knowledge of the native flora 

 to extend their acquaintance to this very common genius, it will 

 have justified its preparation. For Salix, like Carex and Cra- 

 tegus is considered by many Botanists too difficult for any but 

 the specialist. Many competent workers seem to be unable to 

 cope with Salix and there are few even of the larger herbaria in 

 which the willows are correctly determined. The reason for this 

 the writer believes to be not in any inherent difficulty of the group 

 for it is not so difficult as many better known genera, but in the 

 fact that an adequate description of it has never been presented. 

 It is toward filling this need that the present effort is directed. 



The species are all rather similar and variable but the dif- 

 ferences between them are not as inconstant as has been supposed. 

 But the space that has been devoted to them in the manuals is 

 entirely too small for their accommodation even when treated 

 by such a master as Bebb, whose account published many years 

 ago in Gray's manual remains the best treatment of the species 

 within our area. Nor can their character be represented by line 

 drawings such as appear in Britton and Brown's Illustrated 

 Flora; even the lithographs of Sargent's Silva are but little better. 

 The character of a willow leaf is too subtle a thing for the ordinary 

 scientific artist to portray; for that, the camera is necessary. 

 Another fault of most of the descriptions and keys hitherto pub- 

 lished is that they have been written with a complete specimen 

 in mind, as it might be assembled on the herbarium sheet with 

 both kinds of flowers and leaves. But a collector never has a 

 complete specimen and is sure to be balked by lack of the mis- 

 sing parts. It must be admitted, to be sure, that there are some 

 stages of some species which are almost indeterminable. But 

 they are not so numerous as to make it inadvisable to construct 

 keys for the others. 



Any successful treatment of the genus must for the present 

 be local in its scope for Salix is subject to very great geographical 

 variation and a treatment of a given species which would be en- 

 tirely accurate in a given area might be entirely inadequate for 

 the same species if observed a thousand miles from the first lo- 

 cality. The description of Salix nigra given below for example 

 would not cover at all satisfactorily the southern and western 

 plants which go by that name. And yet though the characters 



