Silver Maple (Acer Sacharinum)

 Silver Maple (Acer Sacharinum)

Maple Family: Aceraceae

Description: This tree is 60-100' tall at maturity, forming a short broad trunk and an ovoid to obovoid crown that is defined by long ascending branches of considerable size. Trunk bark of mature trees is gray and rough-textured, consisting of flattened scales and straight to curving furrows. On very old trees, the bark may become slightly shaggy when the scales become curved and somewhat loose. Trunk bark of young trees and branch bark are light gray and more smooth, while twigs are reddish brown, smooth, and covered with scattered white lenticels. Pairs of opposite deciduous leaves occur along the twigs and smaller branches. Individual leaves are up to 6" long and 4" across; they are palmately divided into 5 primary lobes. The primary lobes themselves are often divided into shallow secondary lobes and their margins have a few large teeth. All of the lobes are sharply cleft and pointed at their tips; the primary lobes extend deeply into the interior of each leaf. The upper leaf surface is light to medium-light green and glabrous, while the lower surface is conspicuously whitened and glabrous to mostly glabrous (some hairs may occur along the undersides of the major veins). The slender petioles of the leaves are up to 5" long, light green to red, and glabrous.

Individual trees of Silver Maple can be monoecious or dioecious; trees with perfect florets are rare. Some trees are capable of changing their gender from year to year. Staminate florets occur in small dense clusters about 1/3" across on short lateral spur-twigs; these florets are nearly sessile and they vary in color from yellowish green to red. Individual staminate florets consist of 4 sepals, 4-6 stamens, and no petals. At the base of each staminate cluster, there are several scaly bractlets. Pistillate florets also occur in small dense clusters about 1/3" across on very short peduncles; these florets are nearly sessile and they vary in color from greenish yellow to red. Individual pistillate florets consist of 4 sepals, a pistil with a pair of styles, and no petals. At the base of each pistillate cluster, there are several scaly bractlets. The blooming period occurs from early to mid-spring before the leaves develop. The florets are cross-pollinated by the wind. Fertile female florets soon develop pairs of samaras (seeds with elongated wings). In each pair, the samaras are held about 90° apart from each other (or a little less) and they are joined together at the base. At maturity, individual samaras are 1½-2½" long, becoming light brown; they dangle from slender pedicels and fall to the ground during early summer. The root system produces woody lateral roots that are fairly shallow and widely spreading. The leaves usually become pale yellow during the fall.

Range and Habitat: In Illinois, Silver Maple is a common tree that is found in every county. Habitats consist primarily of moist floodplain woodlands, riverbanks, and swamps. In these types of habitats, Silver Maple is often one of the codominant trees. In drier locations, it is not competitive with Sugar Maple (Acer saccharum) and other trees in the long run because its seedlings are less tolerant of shade. This tree is often cultivated as a landscape plant in yards and parks. In urban and suburban areas, the offspring of these cultivated trees often escape into adjacent areas that are not mowed (e.g., fence rows and vacant lots).