Striped Maple grows as a tall shrub or a small tree that will reach 45 feet in height with 3 to 4 inch diameter stems but frequently is seen no taller than 15 feet. The trunk is short and forked with a few ascending branches forming an open somewhat rounded crown.
Bark: The smooth gray or green-gray bark of Striped Maple bears distinctive light-colored vertical stripes, hence its common name. Bark is reddish brown on new twigs before becoming green-gray and mostly gray with reddish tones on large old stems when the stripes may become obscure.
The leaves are opposite, large, 5 to 8 inches long and much more finely toothed than Mountain Maple, Acer spicatum, which grows nearby in the Garden. The 3-lobed indentations of the leaf are sharply pointed, much more so than A. spicatum (hence the alternate common name of 'goose-foot'). Leaves have a rosy tint when first emerging from the bud due to fine hair on the underside which drops away as the leaf matures. Fall color is yellow.
Twigs are hairless and reddish when young. Bud scales are also reddish. The terminal bud is slightly flattened with a rounded tip. Lateral buds are elongated and held close to the twig.
Flowers: Striped Maple is dioecious, that is, male and female flowers are on different plants. Studies by the US Forest Service indicate the vast majority of trees are male. The flowers are bell-shaped, 1/4 inch long and hang in drooping clusters, which appear after the leaves. The flower has 5 green sepals, 5 greenish-yellow petals with lobes that flare outward and are slightly longer than the sepals. The reproductive parts of male flowers include 6 to 8 stamens with yellow anthers and the female flowers have a 2-carpelled ovary.
Seed: Fertile female flowers produce a winged, paired fruit (a samara or 'key') in late summer, ripening in autumn. The samara pairs are much more widely spread (90 to 120 degrees) than that of A. spicatum. Trees need to be 10+ years old before they produce seed.
Habitat: Striped Maple is an understory tree of mixed woodlands found in moist soils (acid soil preferred) with moderate light. It tolerates deeper shade but becomes spindly. It regenerates from seed.
Names: The genus, Acer, is the Latin word for 'maple'. The species pensylvanicum, means 'of Pennsylvania' where first collected. In the 19th Century the species was named Acer striatum. The author name 'L.' is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. Botanists have recently moved the maples into the Sapindaceae family from the older Aceraceae family. The alternate common name 'Moose Wood' was used historically in Maine and adjacent parts of Canada. See Michaux's notes at bottom of the page.
Comparisons: The most similar species is Mountain Maple, Acer spicatum, which does not have the striped bark, the flower racemes are erect rather than nodding and the leaves have more coarse teeth. Mountain Maple is monoecious - separate male and female flowers but on the same plant.
Above: Plant image ©Gary Fewless, UW Herbarium. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - The drooping clusters of bell shaped flowers distinguishes this maple from A. spicatum. Male flowers shown. 2nd photo - The outer bark furrows and exposes a lighter layer under giving the bark a striped appearance. 3rd photo - bark of an older trunk, almost 4 inches in diameter; the striping still faintly visible.
Below: 1st photo - Male flower detail. 2nd photo - The leaf is much larger, more pointed, and more finely toothed than that of A. spicatum.
Below: 1st photo - When buds break, the new leaves emerge with a rosy tint - quite attractive. Twigs are reddish-brown until the 3rd or 4th year, then forming the typical bark shown above. 2nd photo - Note that the old leaf scars almost form a ring around the twig.
Below: Twigs are hairless and reddish when young with reddish bud scales but the emerging leaves have fine hair.
Below: Leaf comparison of common Maples. Images not to scale.
Notes: Eloise Butler first planted Striped Maple in the Garden on May 28, 1909 with plants obtained from the Park Board Nursery. Striped Maple was listed on Martha Crone's 1951 inventory of plants in the Garden at that time. Striped Maple has been considered native to a few places in Minnesota in some references but this is probably mistaken as neither the MN DNR native plant list nor the University of Minnesota's Checklist of the Vascular Plants of Minnesota (Ref. #28C & W4) list it as a native species. Minnesota native references are probably due to imported and nursery grown plants such as those grown by the Park Board. In nearby Wisconsin, it is found only in distant Door County. Minnesota would be beyond its western-most reach. Its main habitat is the eastern U.S., south as far as Georgia and Eastern Canada. In Ontario it is not found north of 44 degrees.
Heritage Tree: The large specimen near Guidebook station 12 is listed on the Minneapolis Heritage Tree List for its Champion size, being about 42 feet high and with a stem 20 inches in circumference. Another younger tree is right on the path edge near station 4.
Eight species of Maple are found in the wild in Minnesota: A. negundo, Box Elder; A. nigrum, Black Maple; A rubrum, Red Maple; A. saccharinum, Silver Maple; A. saccharum, Sugar Maple; A. spicatum, Mountain Maple; A. ginnala, Amur Maple and A. platanoides, Norway Maple. The latter two are not native but introductions that have naturalized.
Former Garden curator Martha Crone wrote: "The green bark of this tree breaks into a network of furrows, exposing a pale under layer, making the green appear delicately striped with white. The handsome large leaves turn yellow in autumn. The yellow bell-like flowers in long racemes gracefully drooping, appear among the leaves in May. The samaras ripen in autumn. The Striped Maple is most attractive in early spring when its bud scales lengthen and the rosy, down-covered leaves appear. It is difficult to believe that this exquisite maple is a native here, [see notes above on this subject] yet not used more extensively in cultivation. it will thrive in partial shade in with taller trees. Seeds of this tree germinate readily." Published in The Fringed Gentian™, Vol. 4, #2, April 1956.
Uses: Botanist Francois Michaux (son of Andre) wrote in his North American Sylva of 1817-19 (Ref. #26d): "The inferior size of Moose Wood forbids its use in any kind of carpentry, but as it is white and fine grained, the cabinet makers of Halifax employ it instead of Holly, which does not grow in so northern a climate, for forming the white lines with which they inlay Mahogany. Its principal advantage consists in furnishing the inhabitants, at the close of winter, when their forage is exhausted, a resource for sustaining their cattle, till the advancing season has renewed the herbage. As soon as the buds begin to swell, the famished horses and neat cattle are turned loose into the woods, to browse on the young shoots, which they crop with avidity. Poor as this resource may appear, it is not wholly inadequate, since the twigs are tender, and full of saccharine juice." From this may be deduced that the inhabitants saw Moose doing the same thing, and hence 'Moose Wood'.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"