KEY TO GENERA. 



A. Leaf-scars more than one at each node. 



a. Buds pubescent. 



Twigs glaucous Acer. ]5 



Twigs gray, buds brown-felty Fraxinus. 33 



Twigs very small, yellow, scales 2-3 pairs. . .Symphoricarpos. 31 

 Twigs red, scales one pair Cornus. 29 



b. Buds glabrous. 



1. Evergreen Juniperus. 48 



2. Deciduous. 



Leaf-scars circular or oval Catalpa. 34 



Leaf-scars U-shaped Acer. 15 



Leaf-scars more or less semicircular. 



Pith rhomboidal. twigs 4-angled Evonymus. 7 



Pith cylindrical, twigs not angled. 

 Stipule-scars present. 



Joining the leaf-scars Cephalanthus. 32 



Xot meeting Staphylea. 1 * ; 



Stipule-scars absent. 



Leaf-scars meeting Sambucus. 30 



Leaf-scars not meeting ./Esculus. 13 



B. Leaf-scars one at each node. 



a. Plants armed with prickles or thorns. 

 1. Thorns representing branches. 



Bearing leaf-scars below, thorn-like at apex. 



Leaf-scars V-shaped Pyrus. 26 



Leaf -scars oval Primus. 23 



Typical thorns, bearing no leaf-scars. 

 Simple; buds globose, single. 



Color ashy Ioxylon. 37 



Color red or brown Crataegus. 27 



Branched; buds superposed. Gleditsia. 22 



