Juncus effusus L.
Coefficient of Conservatism: 3
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Forb

Widespread in wet ground: marshes, shores, banks of ditches and streams, bog borders and clearings, pastures, etc.; moist open forests and thickets.

This is often a coarser plant than Juncus pylaei, with longer inflorescence branches (except in “congested” forms) and stouter stems. The sheaths are pale brown, often darkening to dark brown or dark reddish brown at the base, but lacking the purple black color often seen at the sheath bases of J. pylaei. The tepals are often shorter than in J. pylaei, ca. 2.2–3.4 mm, and are sometimes shorter than the mature capsule. 

A few collections from Laurium and the Quincy Mine area, in Houghton Co. are the introduced Eurasian subsp. effusus, differing from the native eastern subsp. solutus in having sheath margins dark-edged apically and clearly spreading tepals. Depauperate or fragmentary specimen in this complex can be quite difficult to name.


Alcona County
Alger County
Allegan County
Alpena County
Antrim County
Barry County
Bay County
Berrien County
Calhoun County
Charlevoix County
    Including Beaver Island
Cheboygan County
Chippewa County
Clinton County
Crawford County
Delta County
Emmet County
Gladwin County
Gogebic County
Gratiot County
Hillsdale County
Houghton County
Ingham County
Ionia County
Iron County
Jackson County
Kalamazoo County
Kalkaska County
Keweenaw County
    Including Isle Royale
Leelanau County
    Only on Manitou Islands
Lenawee County
Livingston County
Luce County
Macomb County
Manistee County
Marquette County
Mason County
Mecosta County
Midland County
Newaygo County
Oceana County
Ogemaw County
Ontonagon County
Osceola County
Otsego County
Roscommon County
Saginaw County
Schoolcraft County
St. Clair 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. June 29, 2022. https://michiganflora.net/species.aspx?id=1510.