478 



ILLUSTRATIONS OF THE NATURAL ORDKES. 



gent, and that of the Birch is aromatic. The peculiar odor of 

 Russia leather is said to be owing to a pyroligneous oil obtained 

 from Betula alba, or White Birch. 



921. Ord, Salicaceae {Willow Family). Trees or shrubs, with al- 

 ternate simple leaves, furnished with stipules. Flowers dioecious ; 

 both kinds in aments, and destitute of floral envelopes (achlamyde- 

 ous), one under each bract. Stamens two to several, sometimes 

 monadelphous. Ovary one-celled, many-ovuled ! Styles or stigmas 

 two, often two-cleft. Fruit a kind of follicle opening by two valves. 

 Seeds numerous, ascending, furnished with a silky coma ! Albu- 

 men none. — Ex. Salix (Willow, Fig. 415-419), and Populus (the 

 Poplar). Trees with light and soft wood : the slender, flexible 

 shoots of several Willows are employed for wicker-work. The bark 

 is bitter and tonic, and contains a peculiar substance (Salicine), 

 which possesses febrifugal qualities. The buds of several Poplars 

 exude a fragrant balsamic resin. 



FIG. 1170. Young ament of staminate flowers of a Birch (Betula fruticosa?). 1171. One of 

 ithe three-lobed scales of tbe same, enlarged, showing the flowers (stamens) on the inner side. 



1172. Ament of pistillate flowers. 1173. Branch in fruit. 1173 '. One of the scales with its 

 , three flowers (pistils) seen from within. 1174. Magnified section of one of the two-celled pis- 

 itilB, displaying the ovule suspended from the summit of each ceU. 1175. The pistils (with 



their subtending bract) in a more advanced state. 1176. Magnified cross-section of one of the 

 ■ ovaries. 1177. The mature fruit, with the cell divided vertically ; the single seed occupying 



the cavity ; a mere trace of the other cell being visible. 1178. The seed removed. 1179. The 

 .embryo. 



