ii. Leaves pubescent or white-tomentose, at least beneath;

fruit not a prickly bur.

j. Leaves 2-4 inches long, broadly ovate to suborbicular; fruit a very small capsule, falling in spring. POPULUS, p. 44.

jj. Leaves 4-7 inches long, oblong-lanceolate to obovate; fruit an acorn, falling in autumn. QUERCUS, p. 96.

hh. Teeth fine, 6-many per inch of margin.

i. Leaf-petioles laterally compressed; leaves tremulous. POPULUS, p. 44.

ii. Leaf-petioles terete; leaves not tremulous.

j. Leaf-blades at least 3 times as long as they are broad.

k. Twigs brittle; fruit a very small capsule, falling in spring. SALIX, p. 34.

kk. Twigs tough; fruit a fleshy drupe, falling in late summer or autumn. PRUNUS, p. 152.

jj. Leaf-blades not more than twice as long as they are broad.

k. Leaf-blades about twice as long as they are broad.

l. Margin of leaves singly serrate; fruit fleshy.