Woolgrass

Scirpus cyperinus is extremely variable. A form common in the northern part of its range, south to Iowa, northern Ohio, Maryland, and (in the Appalachians) North Carolina and Tennessee, has bases of the involucral bracts and the involucels blackish, the spikelets sessile or nearly so in glomerules, and the scales relatively short, ovate, and brownish. This form has often been treated as S. cyperinus var. pelius. A more robust southern form, extending north to southern Missouri and Illinois, Kentucky, Virginia, and (along the coast) New Jersey and Massachusetts, has the bases of the involucral bracts and the involucels reddish brown, the spikelets mostly solitary, and the scales relatively long, narrowly elliptic, and reddish brown. This form has often been treated as a distinct species, S. rubricosus (or under the illegitimate name S. eriophorum Michaux). These two morphologies intergrade so extensively that it is not practical to recognize them taxonomically at any rank.

Scirpus cyperinus often hybridizes with S. atrocinctus and S. pedicellatus, forming hybrid swarms. Some plants appear to have characteristics of all three species; the names Scirpus atrocinctus var. grandis Fernald and S. atrocinctus forma grandis (Fernald) D. S. Carpenter are based on such a specimen.

Plants aggregated in dense tussocks; rhizomes branching, short, tough, fibrous. Culms: fertile ones upright or nearly so; nodes without axillary bulblets. Leaves 5–10 per culm; sheaths of proximal leaves green to red-brown; proximal sheaths and blades with septa few to many, conspiucuous or inconspicuous; blades 22–80 cm × 3–10 mm. Inflorescences terminal; rays ascending or sometimes spreading, scabrous throughout or main branches smooth proximally, rays without axillary bulblets; bases of involucral bracts reddish brown, brownish, or blackish, not glutinous. Spikelets in dense cymes of 2–15, central spikelet of each cyme sessile, others sessile or pedicellate, spikelets broadly ovoid, ovoid, or sometimes cylindric, 3.5–8 × 2.5–3.5 mm; scales reddish brown, brownish, or blackish, ovate or narrowly ovate to oblong-ovate or oblong-elliptic, 1.1–2.2 mm, apex apiculate or short-mucronate, apiculus or mucro to 0.1 mm. Flowers: perianth bristles persistent, 6, slender, contorted, much longer than achene, smooth, projecting beyond scales, mature inflorescence appearing woolly; styles 3-fid. Achenes whitish to very pale brown, elliptic or obovate in outline, plumply trigonous or plano-convex, 0.6–0.9 × 0.3–0.5 mm. 2n = 66.

Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que.; Ala., Ark., Calif., Conn., Del., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., Tenn., Tex., Vt., Va., Wash., W.Va., Wis., Wyo.; Mexico.

Fruiting late summer–early fall (Aug–Sep, earlier in s United States).

Marshes, moist meadows, ditches, shallow ponds, frequently growing in disturbed areas; 0–800m.

Eriophorum cyperinum Linnaeus, Sp. Pl. ed. 2, 1: 77. 1762; Scirpus cyperinus var. andrewsii (Fernald) Fernald; S. cyperinus var. pelius Fernald; S. rubricosus Fernald

Scirpus cyperinus (L,.) Kunth, Enum. PL 2: 170. 1837
Eriophorum cyperinum L,. Sp. PI. ed. 2, 77. 1762.
Trichophorum cyperinum Pers. Syn. PI. 1: 69. 1805.
Scirpus thyrsifiorus Willd. Enum. 78, in part. 1809. (Excl. 5. eriophorus Michx.)
Scirpus Eriophorum var. cyperinus A. Gray, Man. ed. 2, 501. 1856.
Scirpus cyperinus a normalis Kuntze, Rev. Gen. 2: 757. 1891.
Scirpus sylvaticus f. cephaloideus Sheldon, Minn. Bot. Stud. 1: 68. 1894.
Scirpus Eriophorum var. condensatus Fernald, Proc. Am. Acad. 34: 501. 1899.
Scirpus cyperinus var. Andrewsii Fernald, Rhodora 2: 16. 1900.
Scirpus cyperinus var. condensatus Fernald, Rhodora 2:16. 1900.
Scirpus cyperinus var. pelius Fernald, Rhodora 8: 164. 1906.
Scirpus cyperinus var. pelius f. condensatus Blake, Rhodora 15: 162. 1913.
Eriophorum cyperinum var. pelium Farwell, Rep. Mich. Acad. 19: 253. 1917.
Eriophorum cyperi[n]um var. pelium f. condensatum Farwell, Rep. Mich. Acad. 21: 360. 1920.
Scirpus cyperinus var. congesta House, Bull. N. Y. State Mus. 233-234: 62. 1921.
Scirpus cyperinus var. pelius f. congestus House, Bull. N. Y. State Mus. 254: 150. 1924.
Scirpus cyperinus f. cephaloideus Beetle, Rhodora 46: 146. 1944.
Culms nearly terete, 1-1.5 m. high; blades numerous, narrowly linear, rather rigid, often equaling the culm; involucral bracts leaflike, 3-5, longer than the loose umbel, 1.5-3 dm. long, the tips of the rays at length drooping ; involucels reddish-brown ; spikelets exceedingly numerous, ovoid, clustered, woolly at maturity, 3-6 mm. long; bristles rust-colored, much longer than the pointless, reddish-brown scales ; achene short-pointed.
Type locality: "In America septentrionali."
Distribution: Wet meadows and swamps; Newfoundland to Virginia, west to Iowa and Saskatchewan.

Scirpus cyperinus, commonly known as woolgrass, is an emergent wetland herb that is native to the eastern United States and eastern Canada. Other common names include cottongrass bulrush and brown woolly sedge.

Woolgrass is not a true grass, despite its common name; it is a type of bulrush (Scirpus). Bulrushes furthermore are not true rushes; they are types of sedges. This sedge is very variable in appearance. In general, it produces short, tough rhizomes and grows in dense clumps. The fertile stems grow upright. There are five to ten leaves per stem. They are up to 80 centimeters long by 1 centimeter wide. The proximal ones have green or reddish sheaths. The inflorescence has upright or spreading branches bearing cymes of up to 15 spikelets each. The spikelet is cylindrical or oval and measures up to 0.8 centimeters in length. It is covered in reddish, brownish, or black scales. The flowers have six long bristles each, making the inflorescence look woolly.

This plant grows in many types of wet habitat, such as marshes and ponds. It can be found in disturbed habitat, such as ditches.

This plant often hybridizes with its relatives Scirpus atrocinctus and S. pedicellatus.

Native Americans used this plant for a number of purposes. The Ojibwa people used it to make bags and mats, and the Potawatomi people used it to stuff pillows.