gg. Leaf buds with 2 or more pairs of scales visible.
h. Bundle-scars usually 3, distinct, separated. ACER, p. 174.
hh. Bundle-scars many, minute, more or less confluent in a U-shaped line. FRAXINUS, p. 211.
ee. Leaf-scars 1 at a node, i.e., alternate.
f. Bundle-scars 1-3.
g. Bundle-scar only 1, or appearing as 1.
h. Twigs bright green, spicy-aromatic; bundle-scar appearing as a horizontal line; terminal bud present; pith homogeneous. SASSAFRAS, p. 139.
hh. Twigs brownish, not spicy-aromatic; bundle-scar appearing as a large dot; terminal bud absent; pith chambered. CELTIS, p. 131.
gg. Bundle-scars 3 or in 3 compound, but distinct groups.
h. Terminal bud present.
i. Stipule-scars present.
j. First scale of lateral bud directly in front, i.e., exactly above the center of the leaf-scar; twigs brittle; pith somewhat star-shaped in cross-section. POPULUS, p. 45.
jj. First scale of lateral bud not directly in front, i. e., to one side of the center of the leaf-scar; twigs not brittle; pith circular in cross-section. PRUNUS, p. 153.
ii. Stipule-scars absent.
j. Buds bright to dark red, the terminal 1/8 - 1/4 inch long.
k. Branches contorted, bearing many short, spur-like branchlets; fruit an apple an inch or more in diameter, light green. PYRUS, p. 143.
kk. Branches not contorted, not bearing short, spur-like branchlets; fruit berry-like, 1/2 inch long, blue-black. NYSSA, p. 209.
jj. Buds brownish to gray, the terminal exceeding 1/4 inch in length.
k. Buds narrow-conical, sharp-pointed; leaf-scars small, narrowly crescent-shaped; twigs about 1/16 inch thick; pith homogeneous; fruit berry-like, not present. AMELANCHIER, p. 149.
kk. Buds broadly conical to ovoid, blunt-pointed; leaf-scars conspicuous, broadly heart-shaped; twigs about 1/4 inch thick; pith chambered; fruit a nut, often present. JUGLANS, p. 61.
hh. Terminal bud absent (sometimes present on short shoots of Betula).
i. Stipule-scars present.
j. Bud-scale only 1 visible; twigs brittle. SALIX; p. 34.
jj. Bud-scales 2 or more; twigs not brittle.
k. Bark smooth, close, warty or peeling into papery layers, but not flaky nor rough-ridged.
l. Tip of bud appressed; fruit berry-like. CELTIS, p. 131.
ll. Tip of bud not appressed; fruit not berry-like.
m. Trunk fluted; catkins not present in winter; lenticels not elongated horizontally; low tree or bushy shrub. CARPINUS, p. 83.
Michigan Trees: a Handbook of the Native and Most Important Introduced Species · The Wunder Library — complete classics, free to read, with narration.