Sorbus americana Marshall
Common Name: AMERICAN MOUNTAIN-ASH
Coefficient of Conservatism: 4
Coefficient of Wetness: 0
Wetness Index: FAC
Physiognomy: Nt Tree

Sorbus americana A. A. Reznicek

Swamps (both cedar and deciduous) and stream banks; mixed forests, especially at borders, as on bluffs along Lake Superior.

Specimens of S. decora with more prolonged acute apices on the leaflets than is often the case are frequently misidentified as S. americana if one is not familiar with the overall lanceolate, longer leaflets of the latter species (usually ca. 4 times as long as broad). Checking several representative leaflets in case of doubt should be sufficient to decide on which side of the length-width ratio a specimen belongs (3.2 apparently is a nearly certain dividing line, as indicated in the key).

Locations

Alger County
Baraga County
Charlevoix County
    Only on Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Crawford County
Delta County
Emmet County
Gogebic County
Houghton County
Iron County
Keweenaw County
    Including Isle Royale
Lake County
Luce County
Mackinac County
Marquette County
Ontonagon County
Osceola County
Roscommon County
Schoolcraft County
Wexford County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 17, 2017. http://www.michiganflora.net/species.aspx?id=2569.