Sorbus americana

Sorbus americana

The tree species Sorbus americana (syn. Pyrus americana) is commonly known as the American Mountain-ash. It is a relatively small (height 12 meters / 40 feet) deciduous perennial tree, native to northern North America and the Appalachian Mountains. Its conspicuous white spring flowers and winter persistent orange fruit make it one of our most recognizable trees.

The American mountain-ash and related species (most often the European Mountain ash, Sorbus aucuparia) are also referred to as rowan trees. The rowans were thought by the Celts and other primitive peoples of The British Isles to have magical properties.

Description

The American Mountain-ash attains its largest specimens on the northern shores of Lake Huron and Lake Superior.

It resembles the European Mountain-ash, Sorbus aucuparia.

  • Bark: Light gray, smooth, surface scaly. Branchlets downy at first, later become smooth, brown tinged with red, lenticular, finally they become darker and the papery outer layer becomes easily separable.
  • Wood: Pale brown; light, soft, close-grained but weak. Sp. gr., 0.5451; weight of cu. ft., 33.97 lbs.
  • Winter buds: Dark red, acute, one-fourth to three-quarters of an inch long. Inner scales are very tomentose and enlarge with the growing shoot.
  • Leaves: Alternate, compound, unequally pinnate, six to ten inches long, with slender, grooved, dark green or red petiole. Leaflets thirteen to seventeen, lanceolate or long oval, two to three inches long, one-half to two-thirds broad, unequally wedge-shaped or rounded at base, serrate, acuminate, sessile, the terminal one sometimes borne on a stalk half an inch long, feather-veined, midrib prominent beneath, grooved above. They come out of the bud downy, conduplicate; when full grown are smooth, dark yellow green above and paler beneath. In autumn they turn a clear yellow. Stipules leaf-like, caducous.
  • Flowers: May, June, after the leaves are full grown. Perfect, white, one-eighth of an inch across, borne in flat compound cymes three or four inches across. Bracts and bractlets acute, minute, caducous.
  • Calyx: Urn-shaped, hairy, five-lobed; lobes, short, acute, imbricate in bud.
  • Corolla: Petals five, creamy white, orbicular, contracted into short claws, inserted on calyx, imbricate in bud.
  • Stamens: Twenty to thirty, inserted on calyx tube; filaments thread-like; anthers introrse, two-celled; cells opening longitudinally.
  • Pistil: Two to three carpels inserted in the bottom of the calyx tube and united into an inferior ovary. Styles two to three; stigmas capitate; ovules two in each cell.
  • Fruit: Berry-like pome, globular, one-quarter of an inch across, bright red, borne in cymous clusters. Ripens in October and remains on the tree all winter. Flesh thin and sour, charged with malic acid; seeds light brown, oblong, compressed; cotyledons fleshy.

Distribution

Native to northern North America; Eastern Canada:
Canada - New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec
Northeastern U.S.A.: United States - Connecticut, Indiana, Maine, Massachusetts, Michigan, New Hampshire, New York, Pennsylvania, Vermont, West Virginia
North-Central U.S.A.: United States - Illinois [n. (Ogle Co.)], Minnesota, Wisconsin
Southeastern U.S.A.: United States - Georgia, Maryland, North Carolina, Tennessee, Virginia
Sorbus americana is listed as endangered by the State of Illinois.

Ecological aspects

The berries look as if they might be good to eat, but it is evident that the birds do not find them so. They are sour, bitter, and of a disagreeable flavor, and go untouched by birds until no other fruit is within reach.

Cultivation

Prefers a rich moist soil and the borders of swamps, but will flourish on rocky hillsides.

See also

  • Rhus glabra (Smooth Sumac) - similar leaf pattern arrangement.

References

External Links

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