Chestnuts, horse chestnuts, and Ohio buckeyes
Occasionally people ask about the edibility of chestnuts. In almost every case the 'chestnut' turns out to be the non-edible horse-chestnut or buckeye.
True American chestnut (Castanea dentata) is rare here. It has been virtually eliminated from much of its former native range due to a fungal blight. Some trees that have been planted outside of that native range remain uninfected. Some of these trees can be seen at the University's Landscape Arboretum near Chanhassen. But with so few trees, pollination is poor and few nuts are produced.
The horse-chestnut (Aesculus hippocastanum), a European native, is occasionally seen as a planted ornamental shade tree, but Ohio buckeye (Aesculus glabra) is the most common of the three. Ohio buckeye is an American native and grows in woods as close as northern Iowa, northern Illinois, and Michigan. It is sold locally in nurseries and has been planted in southern Minnesota as a shade tree.
The following illustrations and descriptions should aid identification:
Ohio buckeye (Aesculus glabra)
Ohio buckeye is a slow-growing, round-headed tree that grows up to 50 feet high. Large, showy, upright flower clusters appear in early June. The flowers are creamy yellow and lack fragrance. Fruits become conspicuous on the tree in late summer and fall. Their husks have thick, knobby spines. Usually a single, rounded, shiny brown seed is produced in each fruit.
The color, shine, and size of this seed has been said to resemble a buck's eye. Leaves have a good green color in summer and turn golden and orange in the fall. In winter one can identify the Ohio buckeye by its dark brown, dry, scaly buds. These are arranged in pairs, opposite from each other, except for a larger single one at the ends of the twigs.
Remember: Ohio buckeye nuts are not edible.
Horse-chestnut (Aesculus hippocastanum)
Horse-chestnut is similar to Ohio buckeye but is not quite as hardy and does not grow as tall. It also differs in having larger flower clusters and cream-colored flowers. Its leaves are typically larger and divided into 7 leaflets. Its fruit husks are not as spiny as Ohio buckeye husks. In winter the Horse-chestnut has large, sticky terminal buds.
Remember: Horse-chestnut nuts are not edible.
American chestnut (Castanea dentata)
American chestnut is a more upright tree with a fairly straight trunk when young. With age it develops a broad, rounded, dense crown. Its drooping, cylindrical, cream-colored male flower clusters emit a noticeable fragrance when they bloom in July. The fruits are often paired or clustered and covered with many thin spines. They resemble spiny burs. Each fruit has 2 or 3 edible chestnuts. These tear- dropped-shaped seeds are flattened, pointed, and shiny brown in color. They are edible when ripe. The leaves are simple with curved teeth. They are a shiny yellow-green above with a paler green underside. Fall color is yellow. The twigs in winter are more slender than the twigs of the other two trees. They also have buds arranged singly along the stem in an alternate arrangement.