Fact Sheet No. 241, UMaine Extension No.2194
Prepared by David E. Yarborough and Timothy M. Hess, The University of Maine Orono, ME 04469. Replaces March 1997 by Tom Degomez, David Yarborough and Christopher Campbell. Revised April 2002.
Grey Birch, Betula populifolia
Slender tree with smooth white bark. Leaves dark green, triangular with a long tapering tip, 1.5″-2.5″ long and 1″- 2″ wide. Buds have sharp points that point away from the twig. Unisexual flowers, male catkins are pre-formed in the summer and over winter, 1.5″ to 2.5″ long when mature in the spring; female catkins 0.5″ long and slender. The fruit’s thin wings broader than the nutlet. Prefers dry, upland soils.
Alder, Alnus rugosa
Small shrub 5′ to 20′ tall or a tree up to 40′. Bark dark brown and speckled with white streaks, twigs smooth to somewhat hairy, reddish-brown with scattered white lenticels. Buds blunt tipped, reddish- brown and stalked with two scales. Egg-shaped, alternate leaves, dark green, hairless and wrinkled above, whitened, dull and somewhat hairy beneath. Margin double-toothed and undulating. Unisexual flowers; male catkin is 2″-4″ long and female catkin is 0.5″-0.75″ long. Nuts tiny and winged borne in a distinctive persistent cone-like structure. Prefers moist soils.
Willow, Salix spp.
Shrubs or trees. Twigs slender with alternate, single scale buds pressed against the twig. Slender leaves 2″-7″ long and pointed, shiny and dark green above and paler beneath, margins toothed with short leaf stalks, prefers moist soils. Unisexual flowers are borne in catkins on separate plants.
Red Maple, Acer rubrum
Multi-stemmed bush in the open with light gray bark and shiny, red, hairless twigs dotted with white lenticels. Leaves opposite with 3-5 lobes, 3″-4″ long with sharp angled lobes, dark green above and whitened underneath. Flowers appear in clusters in April, before leaf buds open. Male flowers, yellow-red, and female flowers bright scarlet, usually appear on separate trees. Prefers wetter soils.
Aspen, Poplar, Populus tremuloides
Twigs slender with scattered orange lenticels, slightly angled with buds shiny, hairless, dark brown and narrow. Smooth, grayish-green bark with a whitish bloom. Leaves alternate, heart-shaped, upper sides dark blue-green with underside a dull green. Flattened shape of petiole causes leaves to shake in the slightest breeze. Unisexual flowers, male and female catkins of about equal size appear on different trees.
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© 1997, 2002
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