132 KEY TO GENERA AND SPECIES 



194. Lower surface of the leaf green and hairy. A 

 form of the Rock Maple. Western New 

 England southward and westward. (Fig. 

 252.) Black Rock Maple, Acer saccharum 

 var. nigrum (Michx. f .) Britton. 



Fig. 253. Horse-Chestnut. 



HORSE-CHESTNUT, BUCKEYE. Leaves opposite, 

 palmately compound. Several species of 

 Buckeye from farther west are occasionally 

 planted; these all differ from the common 

 Horse-chestnut in having 4 petals instead 

 of 5- 



