558 A TEXT-BOOK OF BOTANY. 



and currants. The cultivated currants are varieties of Ribes 

 rubrum: 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 prosfratmu) has a very 

 fetid odor and it is said that the flowers of the buffalo currant 

 (Ribes aiirenm) contain hydrocyanic acid. 



e. HAMAMELIDACE^ OR WITCHHAZEL FAMILY.— 

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

 tropical countries. 



Hamamelis virginiana, or witchhazel, the leaves and bark 

 of which are used in medicine, 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, but not ripe, capsules of the preceding year are still 

 present (Fig. 313). 



The forked branches of the witchhazel, as also the twigs of 

 the peach and other plants, are used in various parts of the 

 United States for detecting the presence of underground water. 

 These are operated somewhat as follows : The branched arms 

 are held by the operator in a horizontal position and as the operator 

 surveys the field, it is supposed the main stem will dip in the 

 direction indicating either underground water, petroleum, etc. It 

 is the honest belief of the operators that the working of the rod 

 is influenced by agencies — usually regarded as electrical currents 

 following underground springs of water — that are entirely inde- 

 pendent of their own bodies, and many uneducated people have 

 implicit faith in their ability to locate underground waters in this 

 way. Hov/ever, it is held by scientists that the operation of the 

 divining rod is generally due to the unconscious movements of the 

 body or muscles of the hand. 



Liqiiidambar Styraciflua or sweet gum-tree of the Atlantic 

 coast of the United 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 



