Michigan Trees: A Handbook of the Native and Most Important Introduced Species
d. Leaves coarsely and sparsely toothed or notched; bark not
longitudinally white-striped; large trees.
e. Twigs coarse; petioles exuding a milky juice when cut; wings of fruit diverging by nearly 180°; bark of the trunk closely fissured, not scaly. _A. platanoides_, p. 189.
ee. Twigs slender; petioles not exuding a milky juice when cut; wings of fruit diverging only slightly; bark of the trunk deeply furrowed, often cleaving in long, thick plates. _A. saccharum_, p. 181.