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Marshes, muddy ditches, shallow water, margins of ponds and wet ground.
In marshes with Acorus calamus, Alisma subcordatum, Iris virginica shrevei, Phragmites australis, Rumex vertcillatus, Sagittaria latifolia, Scirpus validus creber, Sium suave, Typha latifolia.
Quebec and Nova Scotia west to British Columbia, south to VA, IN, OK, and CA.
Herbaceous perennial to 1.5 m high. Emersed leaves alternate, to 1.2 cm wide and up to 80 cm long. Floating leaves, when present, of similar dimensions, basal, flat, and limp. Flowers small, in globular heads: the lower typically pistillate, stigmas 2; the upper staminate; the inflorescence angled at the nodes. Fruits beaked achenes more than 3.5 mm thick, in spiky globular heads to 4 cm across.
Flowers late May to late August
Wetland indicator: Obligate
The presence of two stigmas and locules to each ovary separates this species from other members of the genus.
Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of
Northeastern United States
and Adjacent Canada. Second Ed.
The New York Botanical Garden. Bronx, NY
Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.
Winterringer, Glen S. and Alvin C. Lopinot. 1966. Aquatic Plants of Illinois
Illinois State Museum and Illinois Dept. of Conservation
Michael Hough © 2005