Scientific Name
Carex aquatilis Wahlenb.
Common Name(s)
Water sedge
Tribe / Family Name
Cyperaceae
Flowering Period
July to September
Symbol
CAAQ
Description
Water sedge is a cool-season native perennial grass-like plant that is cespitose or rhizomatous; reproduction occurs primarily from rhizomes, but rarely from seeds. Culms range from 20–120 cm in height with reddish tinged bases that are thickened, swollen, or spongy. It has an erect growth habit and stems that are obtusely to sharply triangular (3-angled) and exceeding the leaves. Inflorescences contain 1–4 terminal, staminate spikes usually up to 12 mm long, up to 3 mm wide, and linear; 2–6 lateral, pistillate spikes 1–4 cm long, up to 4 mm wide, erect, sessile or nearly so, and densely flowered (upper ones often androgynous); spikes are spaced out and not crowded into a dense head. Bracts on the lowest inflorescence usually longer than the inflorescence. Perigynia are 2–3.6 mm long, up to 2.3 mm wide, elliptic to obovate, somewhat flattened, glabrous, nerveless or nearly so, and normally speckled with reddish or brownish spots; beaks are entire and roughened or smooth. Pistillate scales are lanceolate, obtuse or acute, often with white-hyaline tips, longer than the perigynia, and red-brown to purple-brown with a pale midstripe. Stigmas 2. Fruit is an achene, lenticular, and yellowish to brownish black. Leaves are up to 7 mm wide, 8–15 per culm, erect, flat or nearly so, basal and cauline, and light green to glaucous-green. Sheaths are somewhat hispidulous or smooth dorsally, thin and usually ruptured ventrally, indistinctly dotted in the fronts, and concave at the mouth.
General Info
Water sedge can be found in wet meadows, swamps, ponds, and lake margins.
Similar Species
Water sedge can look similar to other sedges, such as lakeshore sedge (Carex lenticularis), Nebraska sedge (Carex nebrascensis), firethread sedge (Carex scopulorum var. prionophylla), and mountain sedge (Carex scopulorum). To differentiate these four sedges from water sedge, look at the light green and readily deciduous nerved perigynia of lakeshore sedge; the bidentate beak at the tip of the perigynia of Nebraska sedge; and bracts that are shorter than the inflorescence of both firethread sedge and mountain sedge.
Picture of growth habit.
Inflorescence consists of 1-4 terminal, staminate spikes, and 2-6 lateral, pistillate spikes.
Close-up picture of perigynium and stigmas.
Illustration of water sedge. USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. <i>An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols</i>. Charles Scribner's Sons, New York. Vol. 1: 422.