286 BOTANY AND PHARMACOGNOSY. 



(Tiarella cordifolia), alum root (Heuchera americana), golden 

 saxifrage {Clirysospleiiiiim), grass of Parnassus {Parnassia), 

 mock orange {Fhiladelphus coronarius) and the wild hydrangea 

 {Hydrangea arhoresccns). 



The plants are rich in tannin, as the alum root of Eastern and 

 Central North America, which contains lo to 20 per cent, of 

 tannin. A glucoside hydrangin, a volatile oil, and possibly also 

 a saponin are found in " seven barks " or wild hydrangea {H. 

 arhorcscens) ; a glucoside is also found in the root of garden 

 hydrangea (//. panicidata grandiflora) . 



d. GROSSULARIACE^ OR GOOSEBERRY FAMILY. 

 The family includes the single genus Ribes. These are more or 

 less spinous shrubs with alternate or fascicled, more or less pubes- 

 cent, 3- to 7-lobed petiolate leaves. The flowers are solitary, as 

 in gooseberry or in racemes, as in the currants. The fruit is an 

 inferior globular berry. The cultivated currants are varieties 

 of Ribes riibnini: the cultivated gooseberries are varieties of 

 R. Uva-crispa. Both of these plants are natives of Europe and 

 Asia and have escaped from cultivation in the United States and 

 Canada. The fruits contain fruit-acids and fruit-sugars and are 

 used in a variety of ways. The fetid currant (Ribes prostratuni) 

 has a very fetid odor and it is said that the flowers of the buffalo 

 currant (Ribes aureum) contain hydrocvanic acid. 



e. HAMAMELIDACE.^ OR WITCHHAZEL FAMILY. 

 The plants are shrubs or trees and are most abundant in sub- 

 tropical countries. 



HainameUs virgimana, or witchhazel, the leaves (p. 610) and 

 bark (p. 527) of which are official, is a shrub which is especially 

 characterized by its asymmetric, undulate leaves and by its produc- 

 ing flowers in the autumn when the leaves are falling and the 

 mature, 1mt not ripe, capsules of the preceding year are still 

 present (Fig. 264). 



Liquidambar Styraciflna or sweet gum-tree of the Atlantic 

 coast of the L^nited States and Mexico, is a tall tree with charac- 

 teristic cork-wings on the branches ; 3- to 7-lobed, petiolate. finely 

 serrate leaves ; monoecious flowers, and a spiny, globular, capsular 

 fruit. The tree yields a balsam allied to the official styrax (p. 

 679), which is obtained from a very similar tree (L. orientalis). 



