Tree to 30 m tall Leaves: opposite, bright green, 8 - 16 cm long, 10 - 18 cm wide, five-lobed, few-toothed. A milky sap is exuded from the stalk. Fall color is yellow to orangish brown. Flowers: bisexual or with male and female flowers on different plants (dioecious), borne in branched clusters, yellowish green. Fruit: winged (samara), paired, 3.5 - 5 cm long, with wings spreading to almost 180 degrees. Bark: dark gray with close fissures and interlacing ridges. Twigs: greenish to light brown, shiny. Terminal buds: short-stalked, yellowish green to reddish brown, about 6 mm long, blunt-tipped, with ridged scales. A milky sap is secreted from damaged buds.
Similar species: Acer saccharum and Acer nigrum have pointy buds, lack a milky sap exuding from the leaf stalk, and have samara wings that are not spread as far apart as the wings of Acer platanoides samaras. Acer pseudoplatanus is sometimes confused with A. platanoides, but A. pseudoplatanus has buds that remain green through winter, samara wings spreading only 60 degrees, and flaking bark that reveals orangish brown inner bark.
Flowering: April to mid May
Habitat and ecology: Has escaped cultivation in disturbed sites and woods near urban areas.
Occurence in the Chicago region: non-native
Notes: Acer platanoides is frequently planted as a street tree due to its adaptation to many soil types and tolerance for hot, dry conditions and air pollution. However, the tree has invaded some natural areas, where it can outcompete our native Acer saccharum.
Etymology: Acer is derived from a Latin word meaning sharp, which refers to the hardness of the wood. Platanoides refers to its resemblance to the genus Platanus.
Author: The Morton Arboretum
Indiana Coefficient of Conservatism: C = null, non-native
Wetland Indicator Status: UPL
Diagnostic Traits: Leaves simple, palmately lobed and veined, the sinuses of principal lobes entire; petioles with milky sap; flowers with conspicuous petals (ca. 4-7 mm); fruits widely diverging (>120 degrees), mostly 4-5 cm long.
Tree with widely spreading crown; lvs much like those of no. 2 [Acer saccharum Marshall], with 5-7 sharply acuminate lobes and few large teeth; juice milky (best seen at base of a detached petiole); fls yellow-green, in erect, pedunculate, rounded corymbs; pedicels glabrous; pet obovate, 5-6 mm, spreading; stamens seated on the disk; mericarps of the fr 3.5-5 cm, scarcely distended over the seed, the wings divergent at an angle of nearly 180л 2n=26. Native of Europe, often found as an escape from cult. in vacant lots, and now spreading into successional forests. Apr., May.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.