THE WILLOW FAMILY. 161 



XXI. THE WILLOW FAMILY. SALICACEJE. 



MATERIAL REQUIRED. 



Branches of the earliest flowering willow, Salix discolor, Muhl., gath- 

 ered in the early spring before the leaves appear. Specimens 

 with both staminate and pistillate flowers are wanted. (Salix 

 cordata, or other species may be substituted.) Similar branches 

 of different kinds of poplar, Populus tremuloides, Michx., and 

 other species. 



WILLOWS. 

 General Characters. 



Beginning with the willows, observe the various exter- 

 nal characters, such as 



1. Form and structure of buds. 



2. Color of the bark. Is it smooth or rough ? 



3. Texture of the twigs. Are they lithe or brittle ? 



NOTE. Such characters are frequently of much more impor- 

 tance than they appear to be at first sight. The twigs of some 

 species of willows are extremely brittle at the base, and being 

 easily detached serve as a means of propagation ; while their color 

 and surface are sometimes so characteristic as to become an impor- 

 tant factor in classification. 



Flowers. 



I. Examine first the staminate catkins. 



1. Ascertain what constitutes the individual flower. 



(Each flower is subtended by a small hairy scale.) 



Under a lens determine 



a. The shape of the scale. 



b. Whether the margin is cut or entire. 



