Part 7

e. Margin of leaves finely serrate. VIBURNUM, p. 229.

ee. Margin of leaves distinctly lobed. ACER, p. 172.

aa. Leaves compound.

b. Leaves alternate.

c. Leaves simple-pinnate.

d. Branchlets armed with short, sharp prickles. ROBINIA, p. 169.

dd. Branchlets unarmed.

e. Leaflets entire with the exception of 2 or more coarse, glandular teeth at the base. AILANTHUS, p. 171.

ee. Leaflets serrate the entire length.

f. Upper leaflets less than 1 inch broad.

g. Trunk and large branches armed with stout spines; leaflets 3/4-1-1/2 inches long. GLEDITSIA, p. 165.

gg. Trunk and large branches unarmed; leaflets 2-3 inches long. PYRUS, p. 142.

ff. Upper leaflets 1-5 inches broad.

g. Leaflets 5-11; pith homogeneous. CARYA, p. 66.

gg. Leaflets 11-23; pith chambered. JUGLANS, p. 60.

cc. Leaves bi-pinnate.

d. Trunk and large branches armed with stout spines; leaflets 3/4 - 1-1/2 inches long, GLEDITSIA, p. 165.

dd. Trunk and large branches unarmed; leaflets 2 - 2-1/2 inches long. GYMNOCLADUS, p. 163.

bb. Leaves opposite.

c. Leaves pinnately compound; fruit a samara.

d. Leaflets 3-5; samaras paired. ACER, p. 172.

dd. Leaflets 7-11, exceptionally 5; samaras not paired. FRAXINUS, p. 210.

cc. Leaves digitately compound; fruit a prickly bur. AESCULUS, p. 194.

WINTER KEY TO THE GENERA

a. Leaves persistent and green throughout the winter, needle-shaped, awl-shaped or scale-like.

b. Leaves in clusters of 2-5, sheathed. PINUS, p. 5.

bb. Leaves solitary, not clustered.

c. Leaves opposite.