VITACEJE 499 



Key to Most Important Species of Vitis^ 



Skin of mature berry not separating freely from the pulp, Vitis vinifera 



(Old World grape). 

 Skin of mature berry separating readily from the pulp. 



Nodes vsdthout diaphragms (Fig. 207, A) ; tendrils forked, VUis rotundifolia 



(Southern fox grape). 

 Nodes with diaphragms (Fig. 207, B); tendrils forked. 

 Leaves and shoots glabrous at maturity and without bloom. 



Leaves broader than long; petiolar sinus usually wide and shallow, 



V. rupestris (sand grape). 

 Leaves ovate in outline; petiolar sinus usually medium to narrow, 

 V. riparia (river bark grape). 

 Leaves rusty or white tomentose or glaucous blue below. 



Leaves not covered with a thick, dense felt-like tomentum when 



fully grown, V. astivalis (summer grape). 

 Leaves covered with a dense, thick, felt-like tomentum when fully 

 grown, V. labrusca (Northern fox grape). 



Vitis vinifera (Old-World Grape, Wine Grape, Raisin 

 Grape). — The Old-World grape is not as large a plant as 

 most American species. The leaves are thin, smooth, and 

 three- to seven-lobed; they may be smooth or woolly-hairy 

 when young; the lobes are rounded or pointed, and their 

 margins coarsely toothed. The oval, oblong, or globular 

 berries are in long and broad clusters. 



The varieties of this species have a high sugar content. 

 On this account, they make better wine and raisins than 

 American varieties. American varieties are table grapes; 

 European varieties are wine and raisin grapes. The latter 

 are now grown in California, where the wine and raisin in- 

 dustries have developed to considerable importance. V. 

 vinifera is not resistant to the attacks of Phylloxera, a scale 

 attacking the leaves and roots. American varieties are 

 comparatively more resistant to these insects and on this 

 account are used as stocks upon which European varieties 

 are grafted. 



^The key is adapted from "The Grapes of New York," by Hedrick. 



