CLASSIFICATION OF ANGIOSPERMS. 355 



c. CORNACE^ OR DOGWOOD FAMILY.— The plants 

 are shrubs or trees with simple, opposite leaves, and flowers in 

 cymes or heads, which in the case of the Flowering dogwood 

 {Cornus Horida) are subtended by four large, petal-like, white, or 

 pinkish bracts. 



The bark of Cornus Horida, a shrub or small tree growing in 

 the United States, contains a bitter principle, cornin ; and a small 

 quantity of gallic and tannic acids. 



METACHLAMYDE^ OR SYMPETAL^. 



This is the highest group of plants and is marked by the fol- 

 lowing characters : The corolla is sympetalous ; the flowers are 

 mostly perigynous or epigynous and both the corolla and stamens 

 are borne on the perianth tube. The number of parts is definite, 

 there being 5 sepals, 5 petals, 5 or 10 stamens and 2 or 5 carpels. 

 This sub-class includes but six orders, to which, however, belong 

 a large number of medicinal and economic plants. 



I. ORDER ERICALES. 



The plants of this order are distinguished by the fact tliat the 

 stamens are mostly free from the perianth tube. 



a. PYROLACE^. — The plants are small, mostly evergreen 

 perennials, and are represented in the United States by several 

 genera. 



Chimaphila nmhellata (Prince's pine or Pipsissewa) is a small 

 trailing or creeping plant producing distinct flower- and leaf- 

 branches. The leaves are official (p. 603). The flowers are in 

 small corymbs and the petals are white or "pinkish. In Chima- 

 phila inacidata the leaves are lanceolate, mottled with white along 

 the veins and the flowers are considerably larger. 



With the Pyrolaceae are sometimes grouped the saprophytic 

 plants of the genus Monotropa. There are two representatives of 

 this genus which are common in the United States, namely, Indian 

 pipe {Monotropa uniUora) and false beech-drops {M. Hypopitys) 

 (Fig. 171). The latter contains a glucoside or an ester of methyl 

 salicylate, and a ferment gaultherase. 



