Carex scirpoidea
Paul Slichter

Flora of Oregon

Plants dioecious, rhizomatous or loosely cespitose; culms 5–31(40) cm long, erect or lax, aphyllopodic or phyllopodic.

Leaves to 3.5 mm wide, blades of previous year persistent or not at base of flowering shoots.

Inflorescences spike 1, occasionally 2 or 3, unisexual; female spikes 1.5–4 cm long.

Female scales ovate to lanceolate, about 2.5–3.5 mm long, shorter than, as long as, or longer than the perigynia, reddish brown to purple, with hyaline margin that may be fringed with hairs; sometimes hairy on the back.

Perigynia ovate, (1.5)2–4(5) × 0.9–1.5(1.6) mm, red-brown or purplish, short-hairy especially toward the beak; stigmas usually 3 (occasionally 2).

Achenes trigonous (occasionally lenticular), 1.2–2 × 0.8–1.2 mm.

Circumboreal. 4 subspecies; 3 subspecies treated in Flora.

Carex scirpoidea forms leafy, more or less spreading clumps or turf and produces cylindrical, unisexual, usually solitary spikes. The perigynia and often the female scales are covered with hairs. Mature plants are easily distinguished from C. scabriuscula, which has perigynia that are black, broad, and loose around the achene. Immature plants can be hard to differentiate. Rare C. idahoa may have superficially similar spikes but its perigynia and female scales are glabrous and plants are more strongly rhizomatous. The three subspecies of C. scirpoidea have a continuum of ecological requirements. Carex s. ssp. pseudoscirpoidea grows at the highest, mostly alpine elevations, on the driest sites and diverse substrates. Carex s. ssp. scirpoidea grows on alpine to montane sites with intermediate moisture, on limestone or other non-acidic substrates. Carex s. ssp. stenochlaena grows at low to moderate elevation, wet, weakly acidic sites, not limestone. All three have limited ranges in Oregon.

Flora of North America

as described under Carex scirpoidea

Plants usually cespitose, short to long rhizomatous. Culms erect or lax, 5-35(-40) cm. Leaves: sheaths and bases from previous year´s leaves usually absent; ligules rounded or acute; blades glabrous adaxially. Inflorescences unispicate (very rarely with short, sessile lateral spike of same sex), mostly erect, ellipsoid; primary inflorescence bracts leaflike, rarely scalelike, shorter or longer than inflorescences. Scales red-brown to purple, ovate to lanceolate, to 3.5 × 1.5 mm, shorter than, equal to, or longer than perigynia, margins hyaline, narrow to broad, central midrib extending midway or to scale apex, apex acute to obtuse. Perigynia red-brown, ovate to lanceolate, to 4 × 1.6 mm, as wide as subtending scale, apex tapering or rounded, distal 3/4 hirsute with white hairs; beak 0.1 mm, orifice circular; rachilla absent. Achenes 1-2 × 0.6-1.2, tightly enveloped by perigynia, occupying full width and at least 3/4 length of perigynia. 2n = 62.Subspecies of Carex scirpoidea grow in a variety of habitats in northern North America. Taxa previously recognized as varieties or separate species are treated here as subspecies of C. scirpoidea. Within the C. scirpoidea complex, all subspecies have the same chromosome number, possess similar achene micromorphology and leaf anatomy, interbreed in greenhouse experiments, and have morphologic characteristics that mostly fall within the normal range for C. scirpoidea.

Photo images

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Herbarium specimens

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