Part 6

m. Lenticels conspicuous; pith whitish or brownish; bark easily peeled off in papery layers; buds ovoid. PRUNUS, p. 152.

mm. Lenticels inconspicuous; pith greenish; bark not separable into papery layers; buds narrow-conical. AMELANCHIER, p. 149.

ll. Margin of leaves doubly serrate; fruit not fleshy.

m. Trunk fluted; fruit inclosed within a halberd-shaped involucre. CARPINUS, p. 83.

mm. Trunk not fluted; fruit not inclosed within a halberd-shaped involucre.

n. Bark of trunk gray-brown, broken into narrow, flattish pieces loose at the ends; fruit in hop-like strobiles. OSTRYA, p. 81.

nn. Bark of trunk white, yellow or dark brown, platy or cleaving off in papery layers; fruit not in hop-like strobiles. BETULA, p. 84.

kk. Leaf-blades almost as broad as they are long.

l. Lower side of leaves more or less downy; sap milky; leaves not crowded on short, spur-like branchlets; fruit berry-like, black. MORUS, p. 135.

ll. Lower side of leaves glabrous; sap not milky; leaves crowded on short, spur-like branchlets; fruit a large, green pome. PYRUS, p. 142.

ee. Margin of leaves distinctly lobed.

f. Fruit an acorn. QUERCUS, p.96.

ff. Fruit not an acorn.

g. Leaves fan-shaped, with many fine veins radiating from the base of the blade. GINKGO, p. 3.

gg. Leaves not fan-shaped, without many fine veins radiating from the base of the blade.

h. Leaf-lobes entire.

i. Leaf-petioles 5-6 inches long; leaves lustrous above; twigs not aromatic when bruised. LIRIODENDRON, p. 137.

ii. Leaf-petioles about 1 inch long; leaves dull above; twigs spicy-aromatic when bruised. SASSAFRAS, p. 139.

hh. Leaf-lobes sinuate-toothed to serrate.

i. Leaf-lobes coarsely sinuate-toothed. PLATANUS, p. 141.

ii. Leaf-lobes serrate.

j. Branches armed with stiff, sharp thorns; sap not milky. CRATAEGUS, p. 151.

jj. Branches unarmed; sap milky. MORUS, p. 135.

cc. Leaves opposite or whorled.

d. Margin of leaves entire or only slightly undulate.

e. Leaves 3-5 inches long; spray fine; fruit an ovoid, scarlet drupe. CORNUS, p. 202.

ee. Leaves 5-12 inches long; spray coarse; fruit a long, slender-cylindrical capsule. CATALPA, p. 222.

dd. Margin of leaves serrate to lobed.