Schoenoplectus acutus (Bigelow) Á. Löve & D. Löve
Synonym: Scirpus acutus
Coefficient of Conservatism: 5
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Sedge

Scirpus acutus of Michigan Flora.

On wet shores or more often in shallow water of ponds, lakes, rivers, and ditches; in fens and "fenny" lakes and sometimes relic in open tamarack swamps; on sand, gravel, marl, or peat. Usually in water up to about 1.5 m deep, but plants with culms as long as 4.2 m have been collected in deeper water. May form pure stands, as in S. tabernaemontani, or grow with other marsh species, such as Phragmites australis, Typha spp., S. pungens, S. tabernaemontani. The pedicels are occasionally nearly or quite suppressed, the spikelets therefore ± densely crowded. Dried specimens are especially difficult at times to distinguish from S. tabernaemontani. Even more than usual, one must weigh both choices in the key with the expectation that a plant will fit neither perfectly. Where the two species grow near each other, intermediate hybrids may be expected. There seems to be a tendency for the anthers of S. tabernaemontani to be slightly shorter [1–1.6 (–2.1) mm long] than in S. acutus [(1–) 1.5–2.5 mm]. The flattened pedicels in S. tabernaemontani are scabrous on the two edges and smooth on the sides; in S. acutus, they are sometimes puberulent and/or red-flecked like the scales.


Alcona County
Alger County
Allegan County
Alpena County
Antrim County
Arenac County
Barry County
Benzie County
Berrien County
Branch County
Calhoun County
Cass County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Clare County
Clinton County
Crawford County
Dickinson County
Emmet County
Genesee County
Gogebic County
Grand Traverse County
Hillsdale County
Houghton County
Huron County
Ingham County
Ionia County
Isabella County
Kalamazoo County
Kent County
Keweenaw County
    Including Isle Royale
Lake County
Lapeer County
Leelanau County
    Including Manitou Islands
Lenawee County
Livingston County
Luce County
Mackinac County
    Including Bois Blanc, Mackinac, Round Islands
Manistee County
Marquette County
Mason County
Mecosta County
Missaukee County
Monroe County
Montcalm County
Montmorency County
Muskegon County
Newaygo County
Oakland County
Ogemaw County
Ontonagon County
Osceola County
Presque Isle County
Roscommon County
Schoolcraft County
St. Clair County
St. Joseph County
Tuscola County
Van Buren County
Washtenaw County
Wayne County


MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. July 27, 2021.