Schoenoplectus acutus var. acutus
Family: Cyperaceae
Schoenoplectus acutus var. acutus image
Liz Makings  
Culms dark green, 1-3 m × 2-6 mm, very firm, rarely soft, air cavities in distal 1/4 mostly 0.5 mm wide. Leaves: sheath fronts coarsely pinnate-fibrillose. Inflorescences 2 times branched, branches mostly stiffly ascending. Spikelets 3-40, 6-18 × 3-4 mm. Flowers: perianth bristles 6, equaling achene body; styles 2-fid. Achenes plano-convex. 2n = 36, 38. Fruiting summer. Fresh, often calcareous to brackish marshes, fens, lakes, slow streams, often emergent in water to 1.5 m; 0-2700 m; Alta., B.C., Man., N.B., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon; Alaska, Ark., Colo., Conn., Del., Idaho, Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., Mont., Nebr., N.H., N.J., N.Y., N.C., N.Dak., Ohio, Okla., Pa., R.I., S.Dak., Tex., Vt., Va., Wash., Wis., Wyo.; probably Eurasia.
Perennial herb with 0.5 - 1.5 cm wide rhizomes, colonial 1 - 3 m tall Leaves: basal, three to four. Sheaths dark red basally, deeply V-shaped at the mouth, the fronts membranous, translucent, and splitting, coarse with pinnate fibers. Ligules membranous. Blades one to two, 0.5 - 12 cm long, 3 - 7 mm wide, often shorter than sheath, C-shaped in cross-section to flat. Inflorescence: composed of three to forty spikelets, terminal, branched, open or compact, subtended by bracts. Lowest bract leaf-like, often upright, 1 - 9 cm long, thickly C-shaped in cross-section. Flowers: minute, subtended by a floral scale, lacking sepals and petals, bearing six bristles. Bristles brown, equal to achene body, strap-like, bearing small spines. Stamens three, exserted. Anthers 2 mm long. Pistil one. Style linear, two-cleft. Fruit: a one-seeded achene, dark grayish brown, 2 - 3 mm long (including beak), 1 - 2 mm wide, egg-shaped, beaked, usually flat on one side and convex on the other. Culm: stout, dark green, 1 - 3 m long, 2 - 6 mm wide, circular in cross-section, solid, internally spongy with air cavities. Spikelets: solitary or in clusters of two to eight (never only solitary), 6 - 18 mm long, 3 - 4 mm wide, circular in cross-section, with eight or more floral scales. Floral scales spirally arranged, reddish to orangish brown to straw-colored, sometimes variable on the same scale, often green when young (or sometimes just the midrib), 3 - 4 mm long, 2 - 3 mm wide, egg-shaped with a rounded or pointed and notched apex, awned, minutely hairy-fringed, sparsely or densely spiny-bumpy (or just above).

Similar species: No information at this time.

Flowering: late April to late August

Habitat and ecology: Local in wetlands. Also found in bogs.

Occurence in the Chicago region: native

Etymology: Schoenoplectus comes from the Greek words schoinos, meaning rush or reed, and plectos, meaning twisted, plaited, or woven, referring to the use of the culms for making useful objects. Acutus means "sharpened to a point."

Author: The Morton Arboretum

From Flora of Indiana (1940) by Charles C. Deam
Rather frequent in the lake area in habitats similar to those of the preceding species.


Indiana Coefficient of Conservatism: C = 5

Wetland Indicator Status: OBL