582 



A TEXT-BOOK OF BOTANY. 



leaves are usually alternate, simple or compound and glandular- 

 punctate (Fig. 280, C). 



Zanthoxylum americanum or northern prickly ash is a shrub 

 or small tree with 5- to n -compound leaves, the leaflets being 

 ovate and nearly sessile ; the flowers are dioecious, greenish, and 

 in axillary cymes ; the fruit is a black, 2-valved capsule. Z. Clava- 

 Herculis or the southern prickly ash is a very prickly shrub, which 



FIG. 324. Guaiacum offlcinale: A, flowering and fruiting branch; B, gynaecium in 

 longitudinal section showing the pendulous ovules; C, a seed; D, E, the fruit in longitudinal 

 and transverse sections. After Berg and Schmidt. 



is characterized by having cork-wings on the bark. The leaves 

 are 5- to i7-foliate, the leaflets being ovate and crenulate ; the 

 flowers are in terminal racemes and have a calyx of 4 or 5 sepals, 

 the calyx being wanting in Z. americanum. The bark of these 

 two species is official. 



PILOCARPUS.- -To this genus belong a number of species which 

 are shrubs or small trees and indigenous to tropical America. 

 The leaves are mostly pinnately-compound, the leaflets being 

 coriaceous and entire ; the flowers are small, greenish and in 

 axillary or terminal racemes; the fruit is a i-seeded, 2-valved 



