Acer saccharum aka Sugar Maple

Sugar maple, Acer saccharum, is a deciduous tree in the soapberry family, Sapindaceae. Other common names include rock maple and hard maple. It grows wild across eastern Canada and the eastern and north-central United States. Its range runs south through the Appalachians to Georgia and west to Minnesota and northeast Texas. It is a main tree of the northeastern hardwood forest and the national tree of Canada.

In gardens it usually reaches 40 to 80 feet (12 to 24 m) tall, with a spread of up to about 60 feet (18 m). Wild trees can pass 100 feet (30 m), and some sources cite 120 feet (37 m). The crown is dense and upright oval when young, becoming rounded with age. Growth is slow, though young trees and trees in open sites grow faster. It is long-lived and takes several decades to mature.

The opposite, simple leaves measure 3 to 6 inches (7.5 to 15 cm) and have three to five lobes. They are mid to dark green above and paler beneath. In autumn they turn yellow, orange or red, and interior leaves often stay yellow. Young bark is smooth and grey-brown. Older bark grows dark, furrowed and broken into thick, curling plates. Winter buds are brown, hard and sharply pointed.

Small greenish-yellow flowers hang on slender stalks in early to mid spring. They appear just before or with the new leaves and have little ornamental value. Bees and butterflies visit them for nectar. The fruit is a pair of winged samaras forming a horseshoe shape, about 1 inch (2.5 cm) long. The samaras ripen brown in early autumn, and birds and small mammals eat the seeds.

Sugar maple does best in fertile, moist, well-drained, slightly acidic soil in full sun. It tolerates part shade, and trees need sun to develop good form. It is very cold hardy, to USDA zones 3 to 8 and RHS H7. It copes poorly with compacted soil, restricted roots, high heat, drought and air pollution. Road salt also harms it. Gardeners value it as a large shade or specimen tree for lawns, parks and campuses. Its dense shade weakens lawn grass beneath it, and its roots can lift paving and block drains.

Possible diseases include verticillium wilt, anthracnose, cankers, leaf spot, tar spot and honey fungus. Drought can scorch the leaves. Aphids, borers, scale insects, gall mites and caterpillars may also attack. The strong branches seldom break under wind or ice.

People tap the sap to make maple syrup, and trees are tapped from about 40 years old. Roughly 32 to 40 gallons of sap boil down to one gallon of syrup. The seeds and inner bark have also served as food, and a bark decoction was a folk remedy for diarrhoea. The hard, heavy wood makes flooring, furniture and fuel. The leaves can poison horses because they contain gallic acid.