FAMILIES OF FLOWERING PLANTS. 79 
is a genus of shrubs, the edible nut of which is familiar to - every 
school boy. Carpinus, the American hornbeam or blue beech is a 
handsome tree with extremely hard wood; it has a close relative in 
Fic. 64.—The Black Birch (Betula lenta) showing ripened fertile aments and the spring- 
produced staminate aments. Original. 
Ostrya, the hop hornbeam, which may be distinguished by the hop- 
like fertile aments. Alnus, the alder, is a characteristic swamp shrub 
and it is the first to expand its tassel-like staminate catkins in early 
spring. 
