CORYLUS 



241 



dulous catkins, 1-3 together in the axil of each bract, 2-10 stamens, with 

 or without a perianth, the pistillate in erect, spreading or drooping catkins 

 or in clusters or spikes, pistillate flowers with or without a calyx, adnate to 

 the 1-2-celled ovary, ovules 1-2 in each cavity of the ovary, style 2-cleft 

 or divided; fruit a small, flattened or ovoid samara, mostly 1 -celled and 

 1 -seeded, seed coat membranous, endosperm none. 



KEY TO THE GENERA 



1. Pistillate flowers clustered, not in a spike or 



catkin, fruit an acorn-like nut Corylus 



2. Pistillate flowers in a spike or catkin, fruit not 



acorn-like 



a. Pistillate catkin small, terminal, loose and 



few-flowered, fruit subtended by a 3-cleft 

 wing or enclosed by a sack 



( 1 ) Fruiting bract leaf-like, 3-lobed, bark 



smooth Carpinus 



(2) Fruiting bract closed, sack-like Ostrya 



b. Pistillate catkin compact, many-flowered 



(1) Pistillate bract 3-lobed, 3-flowered, 



bracts and catkins deciduous Betula 



(2) Pistillate bracts 5-lobed, 2-flowered, 



bracts and catkins persistent Alnus 



Corylus Linne 1753 



(Gr. classical name of the hazel, perhaps from Gr. c o r y s, a hel- 

 met, in allusion to the involucre) 



Shrubs or small trees with alternate, broad, serrate or slightly lobed 

 or incised leaves; staminate catkins 1-3 at the ends of twigs of the previous 

 season, expanding long before the leaves, the flowers solitary in the axil 

 of each bract, stamens 4, each filament 2-cleft or forked and each branch 

 bearing an anther sack (making apparently 8 stamens), pistillate flowers 

 several, from scaly buds, terminating early leafy shoots, ovary inferior, 

 crowned with a small adherent perianth, stigmas 2, long and slender; nut 

 ovoid or sub-globose, inclosed in a leafy involucre or husk, consisting of 

 two more or less united and enlarged bracts. 



Key to the Species 



1. Involucre or husk consisting of 2 broad, fringed bracts C. americana 



2. Involucre bracts united and prolonged into a tubular bristly beak 



C. rostrata 



