Ranunculus longirostris Godr.
Coefficient of Conservatism: 4
Coefficient of Wetness: -5
Wetness Index: OBL
Physiognomy: Nt P-Forb

Ranunculus longirostris A. Chartier

In a great diversity of lakes, ponds, slow to rapid streams, rivers, ditches, and pools.

The status of our white-flowered aquatic buttercups in Ranunculus subg. Batrachium is a source of seemingly endless confusion and frustration. It seems excessive to lump our plants with the heterophyllous R. aquatilis, and we refer most of our plants to R. longirostris, but for a few specimens from northern Michigan which appear to be R. trichophyllus Chaix, at least as defined by short styles and achene beaks (see key). The vegetative features sometimes cited as distinguishing these two seem too variable. Many of our specimens, however, are unsuitable for critical determination, and these have all been mapped, for convenience, with R. longirostris. Additional ample fertile collections of this complex, ideally in fruit where the characters are best observed, are much needed.

Vegetative aquatic buttercups with dissected leaves (this species plus R. flabellaris, R. gmelinii, and R. trichophyllus) may be distinguished from all other submersed aquatics with dissected cauline leaves by the combination of alternate leaf arrangement (unlike Myriophyllum, Ceratophyllum, and some others), absence of bladders (unlike Utricularia), and absence of a definite central axis in the leaves (unlike Rorippa aquatica, Proserpinaca, and Myriophyllum). The tips of the leaf segments in R. longirostris and R. trichophyllus bear tiny translucent spicules.


Alcona County
Alger County
Antrim County
Arenac County
Baraga County
Barry County
Benzie County
Berrien County
Branch County
Calhoun County
Cass County
Charlevoix County
    Only on Beaver Island
Cheboygan County
Chippewa County
    Including Drummond Island
Crawford County
Delta County
Eaton County
Emmet County
Genesee County
Gogebic County
Grand Traverse County
Gratiot County
Hillsdale County
Houghton County
Huron County
Ingham County
Ionia County
Iron County
Isabella County
Jackson 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
Macomb County
Manistee County
Marquette County
Mason County
Mecosta County
Menominee County
Midland County
Monroe County
Montmorency County
Muskegon County
Oakland County
Ogemaw County
Ontonagon County
Oscoda County
Otsego County
Ottawa County
Presque Isle County
Roscommon County
Saginaw County
Schoolcraft 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. August 10, 2022. https://www.michiganflora.net/species.aspx?id=2384.