Alpine Bulrush

Foodplant / feeds on
adult of Plateumaris discolor feeds on pollen? of Trichophorum alpinum
Remarks: season: (3-)6(-12)

Plants densely cespitose; rhizomes arching, short. Culms trigonous, 10–40 cm, scabrous proximal to inflorescence. Leaves: basal sheaths gray-brown; distal leaf sheaths concave at mouth; blades 6–9 × 0.4–0.5 mm, much shorter than culms at flowering and fruiting. Inflorescences: spikelets 15–20-flowered, 5.4–8 × 2.2–3.5 mm; bracts equaling or shorter than spikelets, 4.5–7.8 mm, apex mucronate or awned, awn to 3 mm. Spikelets: scales yellow-brown, apex obtuse. Flowers: perianth bristles 6, white, flattened, exceeding achenes by as much as 20 times, smooth; anthers 1.1–1.6 mm. Achenes plano-convex, 1.2–1.6 × 0.5–0.8 mm. 2n = 58.

Alta., B.C., Man., N.B., Nfld. and Labr., N.W.T., N.S., Nunavut; Ont., Que., Sask., Yukon; Alaska, Conn., Maine, Mass., Mich., Minn., Mont., N.H., N.J., N.Y., Vt., Wis.; Europe; c Asia (Kamchatka).

Fruiting summer (Jun–Aug).

Open or shaded, wet, peaty or gravelly fens, bogs, sheltered banks of lakes, ponds, and streams, tending to occur on lime-rich substrates; 0–1400m.

Eriophorum alpinum Linnaeus, Sp. Pl. 1: 53. 1753; E. hudsonianum Michaux; Scirpus alpinus (Linnaeus) Dalla Torre & Sarntheim 1906, not Schleicher ex Gaudin 1828; S. hudsonianus (Michaux) Fernald; Trichophorum alpinum var. hudsonianum (Michaux) Persoon

Scirpus hudsonianus (Michx.) Fernald, Rhodora 8: 161. 1906.
Rriophorum alpinum L. Sp. PI. 53. 1753. Not Scirpus alpinus Schleich. 1821; Gaudin 1828.
Linagrostis alpina Scop. Fl. Cam. ed. 2, 1: 48. 1772.
Eriophorum hudsonianum Michx. Fl. Bor. Am. 1: 34. 1803.
Trichophorum alpinum Pers. Syn. PI. 1: 70. 1805.
Trichophorum alpinum (3 hudsonianum Pers. Syn. PI. 1: 70. 1805.
Trichophorum hudsonianum Nutt. Gen. 1: 36. 1818.
Limnochloa alpina Drejer Fl. Exc. Hafn. 18. 1838.
Scirpus trichophorum Asch. & Graebn. Syn. Mitteleur. Fl. 2 2 : 301. 1904.
Loosely tufted perennial from slender rootstocks; culms 1-4 dm. high, erect, green, trigonous, the angles scabrous, clothed at the base with light brown, imbricate sheaths having hyaline, red-flecked margins; upper sheaths green, the margin of the orifice hyaline, white, abruptlycontracted, the blades 1 cm. long, or occasionally fully developed to 3 dm. long, scabrousmargined, their tip abruptly globular; spikelets 5-7 mm. long, 3 mm. broad, solitary, terminal, many-flowered, terete, ovoid-acute; outer scale 4 mm. long, bracteal, the mucronate tip 2 mm. long, scabrous-margined; inner scales oblong-lanceolate, the midrib broad and green, the margins brown; bristles 6, elongate, 2-2.5 cm. long, ligulate, white; stamens 3; style 4 mm. long, trifid ; achene 1.5 mm. long, 0.75 mm. broad, dark brown, smooth, narrowly obovoid, trigonous, acutely apiculate.
Type locality: "A sinu Hudsonis ad lacus Mistassius."
Distribution: Cold bogs and wet shores of northern Europe and northern North America; Labrador and Newfoundland, south to New York, westward to Montana and Yukon Territory.

Alpine bulrush or cotton deergrass (Trichophorum alpinum) is a species of flowering plant in the sedge family. It has a circumboreal distribution, occurring throughout the northern latitudes of the Northern Hemisphere. It is present in Europe, Asia, and northern North America.

This sedge produces stems up to 40 centimeters (16 in) tall from a short rhizome. The leaves are no more than a centimeter long. The flowers have cottony white bristles that may extend 2 centimeters (0.79 in) past the spikelet.

This plant grows in bogs and calcareous mountain meadows.