VITACEAE .' 185 



Key to the Genera 



Leaves simple. 



Pith of the branches interrupted at the nodes; petals not 

 separating at the summit but falling off as a cap; berry 



spherical, black or bluish black, and edible Vitis, p. 185 



Pith of the branches not interrupted at the nodes; petals 

 separating and expanding before falling off; berry ob- 

 late-spherical in shape, bluish, not edible 



Ampelopsis, p. 194 



Leaves compound, the leaflets palmately arranged 



Parthenocissus, p. 196 



VITIS (Tournefort) Linnaeus 

 The Grapes 



The grapes are climbing or trailing vines, mostly with shreddy 

 bark and branched tendrils opposite some or all of the leaves. 

 The leaves are alternate and simple but often prominently lobed 

 and veined, and the stipules are small and early deciduous. The 

 flowers are dioecious or, rarely, perfect and possess a minute 

 calyx and early deciduous petals which cling together at the 

 top like a cap. The ovary is 2-celled, and the fruit is a pulpy 

 berry which contains a few pear-shaped seeds. 



Grapes are native in warm and temperate regions throughout 

 the world. There are about 50 species, among which possibly 

 20 are native in the United States and 6 in Illinois. They often 

 are difficult to identify botanically. 



Key to the Grape Species 



A tendril or a flower cluster opposite every leaf 



V. Labrusca, p. 186 



Neither a tendril nor a flower cluster opposite every third 

 leaf. 

 Under surface of the leaves rusty pubescent, glaucous, or 



covered with cobwebby pubescence V. aestivalis, p. 186 



Under surface of the leaves glabrous or pubescent but never 

 glaucous or rusty pubescent. 

 Leaves either without lobes or with 2 lateral lobes forming 

 wide sinuses. 

 Under surface of mature leaves more or less densely 



pubescent V. cinerea, p. 188 



Leaves glabrous on the under surface or pubescent only 



along the veins V. vulpina, p. 190 



Leaves with 2 lateral lobes forming acute sinuses. 



Branchlets bright red; berries bloomless V. palmata, p. 191 

 Branchlets not red; berries bloom covered. V. riparia, p. 193 



