WINTER KEY TO THE SPECIES OF ACER

a.Terminal buds usually under 1/4 inch in length.
b.Buds white-woolly; twigs usually with a whitish bloom;opposite leaf-scars meeting; fruit often persistent on thetree until spring.A. negundo, p. [193].
bb.Buds not white-woolly; twigs without whitish bloom;opposite leaf-scars not meeting; fruit not persistent onthe tree in winter.
c.Buds reddish or greenish; twigs bright red.
d.Twigs strictly glabrous; buds glabrous; sphericalflower buds clustered on the sides of the shoot; pithpink; large trees.
e.Twigs rank-smelling when broken; tip of outerbud-scales often apiculate; tips of branches curvingupwards; bark separating into long, thin flakesloose at the ends.A. saccharinum, p. [185].
ee.Twigs not rank-smelling when broken; tip of outerbud-scales rounded; tips of branches not conspicuouslycurving upwards; bark rough-ridged, butseldom forming loose flakes.A. rubrum, p. [187].
dd.Twigs appressed-hairy, at least near the tip; budssomewhat tomentose; spherical flower buds absent;pith brown; shrub or bushy tree.A. spicatum, p. [179].
cc.Buds brownish; twigs brownish or grayish.
d.Buds glabrous, or somewhat pubescent at the apexonly; bark dark gray on the trunk.A. saccharum, p. [181].
dd.Buds hoary-pubescent; bark sometimes almost blackon the trunk.A. saccharum nigrum, p. [183].
aa.Terminal buds usually 1/4-1/2 inch in length.
b.Buds reddish; opposite leaf-scars meeting.
c.Buds conspicuously stalked; bud-scales visible, 1 pair;bark longitudinally white-striped; small tree or largeshrub.A. pennsylvanicum, p. [177].
cc.Buds not conspicuously stalked; bud-scales visible, 2-3pairs; bark not white-striped; large tree.A. platanoides, p. [189].
bb.Buds bright green; opposite leaf-scars not meeting.A. pseudo-platanus, p. [191].

Striped Maple. Moosewood. Whistlewood

1. Winter twig, × 1.

2. Portion of twig, enlarged.