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.

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.