This deciduous tree is 60-140' tall and 3-8' across at the base of the trunk. In open areas, the crown is ovoid and irregular with crooked branches. In forested areas, the crown is smaller and more narrow. There is usually a single central trunk that is straight. On a mature tree, the bark of the lower trunk is loose, scaly, and brown. In contrast, the bark of the upper trunk and branches exfoliates, revealing smooth patches of inner bark that are light gray, light brown, and white. Developing twigs are light green and pubescent; they become glabrous, woody, and orange-brown or light brown with age. The blades of alternate leaves are 4-10" long and similarly across; they have 3-5 palmate lobes and margins that are coarsely dentate. The lobes have pointed tips and broad bases; the concave sinuses between the lobes are wide and shallow. The upper blade surface is light to medium green and glabrous, while the lower surface is more pale and variably pubescent. Young leaves have pubescent lower surfaces, while older leaves are either glabrous or their pubescence is restricted to the major veins. The petioles are up to 6" long, light green, and glabrous or short-pubescent. The base of each petiole is swollen and encircles the bud. Near the base of each petiole, there is a large leafy stipule that is coarsely toothed; it surrounds the twig. American Sycamore is monoecious, producing separate male (staminate) and female (pistillate) florets on the same tree while its leaves are developing. The male florets are arranged together into dense green flowerheads that are globoid in shape, and similarly for the female florets. The blooming period occurs during the spring; the florets are cross-pollinated by the wind. Afterwards, the male flowerheads become detached from the tree and wither away, while the female flowerheads are replaced by light brown seedheads about ¾-1½" across that hang from peduncles up to 6" long. There is usually one seedhead per peduncle; two seedheads per peduncle are uncommon. These seedheads persist on the tree through the winter until they break apart no later than late spring of the following year. Individual seeds are embedded in achenes that are narrowly oblanceoloid, winged, and up to ½" long. At the base of each achene, there is a tuft of long tan hairs. The achenes are distributed by wind and water. The woody root system is widely spreading and branched.