Part 4 (1/2)

cc. Leaves alternate or spirally-whorled.

d. Leaves flattened, soft to the touch.

e. Leaves 1/2 - 1-1/4 inches long, sessile, aromatic; cones 2-4 inches long; bark of trunk with raised blisters containing resin. ABIES, p. 27.

ee. Leaves seldom over 1/2 inch long, short-petioled, not aromatic; cones about 3/4 inch long; bark of trunk without raised blisters. TSUGA, p. 29.

dd. Leaves 4-sided, harsh to the touch. PICEA, p. 19.

aa. Leaves not persistent and green throughout the winter, but deciduous in early autumn.

b. Twigs, branches or trunks armed with stiff, sharp p.r.i.c.kles, spines or thorns.

c. Thorns or spines not exceeding 1/2 inch in length on the branches.

d. Spines in pairs at each node; buds rusty-hairy, 3-4 superposed; fruit a flat pod. ROBINIA, p. 169.

dd. Spines one at each node; buds glabrous, not superposed; fruit orange-like. MACLURA, p. 133.

cc. Thorns or spines much exceeding 1/2 inch in length on the branches.

d. Thorns usually branched, situated above the nodes; lateral buds superposed, the lower covered by bark; fruit a flat pod.

GLEDITSIA, p. 165.

dd. Thorns unbranched on twigs, situated at the nodes; lateral buds not superposed, not covered by bark; fruit a small pome.

CRATAEGUS, p. 151.

bb. Twigs, branches or trunks unarmed.

c. Leaf-scars mainly crowded on short, stout, lateral shoots.

d. Bundle-scar 1; fruit a cone, usually present. LARIX, p. 17.

dd. Bundle-scars 2; fruit a globose drupe falling in autumn.

GINKGO, p. 3.

cc. Leaf-scars distributed along the lateral branches.

d. Leaf-scars (or some of them) 3 at a node, i. e., whorled.

CATALPA, p. 223.

dd. Leaf-scars 1-2 at a node, i.e., not whorled.

e. Leaf-scars 2 at a node, i.e., opposite.

f. Terminal buds 1/2 - 1-1/2 inches long, resin-coated; twigs very stout. AESCULUS, p. 195.

ff. Terminal buds rarely exceeding 1/2 inch in length, not resin-coated; twigs not conspicuously stout.

g. Leaf buds with 1 pair of scales visible.