ANALYTICAL KEY 



g". Old bark light, scaly; calyx wanting. 



Black Ash, FRAXINUS NIGRA (p. io6). 

 e. Flowers appearing with or after the leaves, 

 f. Leaves simple; bark gray; flowers polygamous, 



SuRAR Maple, ACER SACCHARTJM (p, 91). 

 f. Leaves compound, 

 g. Leaves pinnate; flowers dioecious. 



Box Elder, ACER NEGTTNDO (p. 92)- 

 g. Leaves palmate; flowers irregular. 



Buckeye^ AESCtJLXJS GLABRA (p. 92). 

 c. Leaves and branches not opposite, 

 d. Flowers monoecious or dioecious, one or both sorts in catkins (p. 8). 

 o. Flowers appearing decidedly before the leaves, both sorts in catkins- 

 f. Flowers monoecious (.Aider). 

 g. Leaves doubly serrate, rounded at base, usually downy. 



Hoary Alder, ALNUS INCANA (p. 49). 

 g. Leaves regularly serrate, acute at base, usually smooth. 



Smooth Alder, ALNTTS RITGOSA (p, 49). 

 f. Flowers dioecious iPvplar). 

 g. Stigmas slender; catkin scales silky; stamens less than twenty, 

 h. Bud scales smooth, shiny, sharply pointed; catkin scales with deep and 

 nearly equal linear divisions. 



Trembling Aspen, POPTJLtrS TREMTILOIDES (p. 44), 

 b. Bud scales downy, dull brown, rounded or abruptly pointed ; catkin 

 scales with unequal small divisions. 



Large-toothed Aspen, POPTILUS GRAWDIDENDATA (p. 44). 

 g. Stigmas stout and fleshy; catkin scales smooth or nearly so; stamens 

 more than twenty. 

 h. Buds dark brown, very fragrant; stamens thirty or less; capsule 

 two-valved. Balsam Poplar, POPTJLTTS BALSAMIFERA (p. 44). 



h. Buds light brown, very glutinous; stamens sixty or more; capsule 

 3-4 valved. Cottonwood, POPXTLUS DELTOIBES (p. 45). 



e< Flowers appearing with or after the leaves. 

 f. Both sorts of flowers conspicuously in catkins (p. 7). 

 g. Bark smooth, usually papery; lenticels horizontal, conspicuous; flowers 

 monoecious {Birch). 

 h* Bark and twigs sweet and aromatic, 

 i. Bark dark brown, not detaching in filmy layers. 



Sweet Birch, BETULA LENTA (p. 48). 

 i. Bark yellowish or grayish, detaching in filmy layers. 



Yellow Birch, BETULA LTJTEA (p. 48). 

 h. Bark and twigs not sweet and aromatic. 

 i. Bark brownish or reddish. River Birch, BETTTLA NIGRA (p. 48). 

 i. Bark white. 

 j. Bark dull white, not readily exfoliating; leaves triangular, long 

 taper-pointed. Gray Birch, BETULA POPULIFOLIA (p. 49). 



j. Bark creamy white, exfoliating readily; leaves not triangular nor 

 taper-pointed. 



Paper Birch, BETULA ALBA PAPYRIFERA (p. 49). 

 g. Bark roughish, not papery; lenticels not horizontal nor conspicuous, 

 h, Leaves heart-shaped; calyx present. 



Red Mulberry, MORUS RUBRA (p. 53). 

 h. Leaves not heart-shaped; calyx wanting; flowers dioecious (IVillow). 



