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The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.

Fraxinus pennsylvanica Marshall
Coefficient of Conservatism: 2
Coefficient of Wetness: -3
Wetness Index: FACW
Physiognomy: Nt Tree

Fraxinus pennsylvanica B. S. Walters

Swamps and shores, often in areas that are quite wet, at least seasonally, often dominant on floodplains, occasionally invading peatlands, also in upland deciduous forests and old fields.

Plants with leaves and new twigs glabrous have been called green ash, but are not now considered of sufficient taxonomic significance to warrant recognition as a variety or subspecies. Pubescent plants (red ash) are rather easily recognized, but glabrous ones may sometimes be confused with F. americana, especially when one does not have sufficient magnification to see the papillose lower surface of the leaflets in the latter. The distinctive slender petiolules in F. americana usually contrast well with the very short petiolules in F. pennsylvanica, in which furthermore they are often narrowly winged so as to give the leaflets an almost sessile aspect. The leaflets may be paler green beneath than above, but are only very rarely as whitish as in typical F. americana. Waxy flakes or strips peeling from year-old twigs of F. americana contrast with the usually smooth (if not pubescent) twigs of F. pennsylvanica. Natural hybrids between these two species are apparently very rare.


Alcona County
Alger County
Allegan County
Alpena County
Arenac County
    Including Charity Island
Baraga County
Bay County
Benzie County
Berrien County
Cass County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Clare County
Clinton County
Delta County
Eaton County
Emmet County
Genesee County
Gladwin County
Gogebic County
Gratiot County
Hillsdale County
Houghton County
Huron County
Ingham County
Iosco County
Isabella County
Jackson County
Kalamazoo County
Kent County
Keweenaw County
Lake County
Lapeer County
Leelanau County
    Including Fox Islands
Lenawee County
Livingston County
Luce County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Macomb County
Manistee County
Marquette County
Mason County
Menominee County
Midland County
Missaukee County
Monroe County
Montcalm County
Montmorency County
Muskegon County
Newaygo County
Oakland County
Oceana County
Ontonagon County
Osceola County
Oscoda County
Ottawa County
Presque Isle County
Roscommon County
Saginaw County
Sanilac County
Schoolcraft County
Shiawassee County
St. Clair County
St. Joseph County
Tuscola County
Van Buren County
Washtenaw County
Wayne County
Wexford County


MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. January 30, 2023.