24 



A. Cultivated chiefly for fruit. 

 B. Color of fruit red. 



C. Stems slender, trailing ; leaves evergreen. 



D. Apex of leaves acute Oxycoccus- 



DD. Apex of leaves obtuse or retuse. 



macrocarpon 

 CC. Stems stouter though creeping ; branches erect, 



tufted Vitis-Idaea 



CCC. Stems erect, much taller (2-10 feet). 

 D. Leaves small (%-% inch long). 



parvijolium 

 BB. Color of fruit blue or black. 



C. Plant low, >2-3 feet high. 



D. Foliage evergreen. 



E. Leaves small (K-^ inch long) . 



nitidum 

 EE. Leaves larger (K 1 inch long). 



Myr smites 



DD. Foliage deciduous. 



E. Surface of leaves glabrous. 



F. Leaves pale beneath, not 

 shining above . . . , vaciUans 

 v&r.pattidum of corymbosum 

 FF. Leaves not paler beneath (ex- 

 cept sometimes in Pennsyl- 

 vanicum) ; shining, at least 

 above. 

 G. Flowers solitary in the 



axils. 



H. Branches sharply 

 angled. 



Myrtillus 



HH. Branches not 

 angled. 



ccespitosum 

 GG. Flowers in fascicles or 



short racemes. 

 H. Fruit blue, glaucous 



Pe n nsylva n ic u m 

 HH. Fruit black. 



nigrum 



