U.P. TREE IDENTIFICATION KEY
Paper Birch, Yellow Birch, Ironwood, and Musclewood
Betulaceae, The Birch Family
birches form a family with 6 genera
and about 100 species that occur mostly throughout the cooler northern climates.
Most are shrubs. In the U.P. there are four tree-sized species. They all have simple leaves with saw-toothed margins. Family members frequently bear
male catkins which form in the fall
and flower in the spring. Female catkins form in the spring. The two birches
have small samaras shaped like
turkey feet that fall from papery cones. Ironwood and musclewood have unique fruits.
PAPER BIRCH (Betula
Other Names: White Birch, Canoe Birch, or Silver Birch
Key ID Features: Bark, Leaves, Fruit
The bright white, peeling BARK of paper birch make this tree one of the easiest in the northwoods to identify. The only tree commonly mistaken for paper birch is quaking aspen, which sometimes has snow white, smooth BARK but it does not peel. Paper birch LEAVES are 2-3 inches long and have a rounded leaf base. Leaf margins are serrated or double-serrated. The fine TWIGS are purplish with many small white spots called lenticles. This purplish cast and fine twig pattern can be seen in the CROWNS from a distance away, distinguishing it from aspen. Male catkins are about an inch long, The small SEEDS, or samaras, (seed coats in image) are about 1/8 of an inch long. They look like tiny turkey feet and can often be found atop the snow throughout the winter. Paper birch is a sun-loving, short-lived tree that, historically, pioneered recently burned areas. Fire suppression, old age, and an inability to reproduce in the shade have contributed to a dramatic decline of this popular tree. Often growing in PURE STANDS, paper birch can also be ASSOCIATED with upland hardwoods, balsam fir, and swamp forest types. Common pests: gypsy moth, large aspen tortrix, leafminers, skeletonizers, tussock moths, bronze birch borer, drought, old age.
YELLOW BIRCH (Betula alleghaniensis)
Other Names: Gray Birch, Swamp Birch, or Sweet Birch
Key ID Features: Bark, Twig Taste, Habitat, Leaves
Yellow birch has the characteristic papery BARK of birches, but peels in a more shreddy fashion. The BARK is a bronze or shiny brown color. On large trunks, the BARK forms large plates. LEAVES are 3-4 inches long with double-serrate margins. Bruised TWIGS have the smell and taste of wintergreen. The older TWIGS are brown-purple, like paper birch, but the recent twigs are a medium gray. Male catkins are about 1 inch long, form in the fall, and flower in the spring. Small samaras ripen in paper cones, about 1-1.5 inches long, in the late summer. Like paper birch, the samaras look like little turkey feet with hairs on the margins. Yellow birch can grow to HEIGHTS of 80 feet with DIAMETERS of 2-3 feet. It is a common COMPONENT of northern hardwood stands, especially on cooler and moister sites. Hemlock has very similar site requirements. The Latin name in some older books is Betula lutea. Common pests: gypsy moth, leafminers, skeletonizers, tussock moths, bronze birch borer.
Other Names: Hophornbeam or Hornbeam
Key ID Features: Understory Habit, Bark, Leaves, Fruits
Ironwood is a small tree in the UNDERSTORY of northern hardwoods and other upland hardwood stands. It is one of the few species that neither cattle nor deer will browse, so is often "what is left over" in many of our U.P. hardwood stands. The LEAVES and male catkins are like the birches. The FRUITS, however, are much different. Nut-like seeds form inside of light-brown papery sacs about an inch long. The BARK is very shreddy, curling away up and down the stem. In the winter, the light-brown LEAVES often stay on the TWIGS making identification from a distance fairly easy. The TWIGS are slender and usually a brown color. The terminal buds are pointy with several bud scales. The wood is extremely hard, thus the name "ironwood."
Other Names: Hornbeam, Ironwood, Blue Beech, or Water Beech
Key ID Features: Bark, Understory Habit, Leaves, Fruit
The smooth, sinewy, contoured appearance of the slate-gray TRUNK give the appearance of a well-muscled arm or leg, hence the name. The LEAVES are similar to the birches. The male catkins appear in the spring only, unlike the birches and ironwood. The female catkins form interesting CLUSTERS of little nut-like seeds, each with a 3-pointed bract. TWIGS are gray often with light spots. Blunt BUDS may be different sizes. Musclewood is uncommon in the U.P., occurring on moist, rich SOILS in the understory in association with upland hardwoods. Like ironwood, musclewood has very dense, hardwood.
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