Richardson's Sedge

Carex richardsonii is common on the Canadian prairies and in open montane woodlands east of the Cascades. Farther east, it is a rare plant of alvars, tall-grass prairie remnants, and postglacial shorelines, such as those of Lake Iroquois (in Ontario and New York) and Lake Barlow-Ojibway (in Quebec). It is most closely related to, and perhaps the ancestor of, C. concinnoides. Chromosomal data and phylogenetic analysis may help to test that contention.

The long, dark reddish brown sheaths are a conspicuous field mark. Late in the growing season, the leaves often turn dark wine red. This species tends to have low seed set.

Plants loosely cespitose, long-rhizomatous. Culms 14–32 cm. Leaves: basal sheaths dark purplish to reddish brown; blades mostly basal, pale green, shorter than culms, thick, 0.9–3.3 mm wide. Inflorescences: peduncles of proximal pistillate spikes to 7 cm; peduncles of terminal staminate spikes 3.3–15.7 mm; proximal bracts long-sheathing; pistillate spikes 2–4, emerging from cauline nodes, widely separated, ascending, ovoid to ellipsoid or short-cylindric; terminal staminate spikes 17.4–23 × 2.5–3.8 mm. Scales: pistillate scales reddish brown, ovate, apex acute to obtuse, glabrous; staminate scales reddish brown, ovate to obovate, margins silvery-white, apex acute to short-acuminate, scarious. Anthers 2.1–2.6 mm. Perigynia obovoid to oblanceoloid, 2.4–2.9 × 1–1.3 mm, base tapering, pubescent with straight white hairs; beak straight, 0.2–0.5 mm. Stigmas 3, flexuous, thin, strongly papillose. Achenes ellipsoid to obovoid, 1.7–1.8 × 1.1–1.2 mm. 2n = 52.

Alta., B.C., Man., N.W.T., Ont., Que., Sask.; Ill., Ind., Iowa, Md., Mich., Minn., N.Y., N.Dak., Ohio, Pa., S.Dak., Vt., Wis., Wyo.

Fruiting late spring–summer (late May–mid Jul).

Vernally moist (often drying later in the season), open woodlands, alvars, floodplain edges, prairies, and basic and acidic outcrops; 50–1400m.

Carex richardsonii R. Br.; Richards, in Frankl. Journey 751. 1823.
Loosely cespitose, in small clumps, the rootstocks long, ascending, slender, tough, brownish-black, scaly, the culms erect or somewhat curved, slender, 15-35 cm. high, central and phyllopodic, about the length of the leaves, triangular, strongly roughened on the angles above, dark-brownish at base; sterile shoots aphyllopodic; leaves with well-developed blades 6-10 to a fertile culm, clustered near the base, the blades thick, light-green, erect or somewhat spreading, 1-2.5 dm. long, 2-2.5 mm. wide, flattened or channeled towards base, long-tapering, rough on the margins, especially towards the apex; fertile culms also bearing above the welldeveloped leaves 4 or 5 bladeless or nearly bladeless, reddish-purple sheaths with hyaline margins; blades of sterile culms rather narrower and shorter than those of fertile; sheaths tight, concave at mouth, the ligule short; staminate spike linear or subclavate-linear, noticeably peduncled, 10-25 mm. long, 2-3.5 mm. wide, the scales obscurely ciliate, obovate, mostly obtuse, brownish-purple, with broad white-hyaline margins, the midvein obscure; pistillate spikes usually 2, erect, approximate, on included or rarely somewhat exserted peduncles, linear, 10-22 mm. long, 2-4 mm. wide, closely IO-25-flowered, the perigynia ascending in few rows; bracts bladeless, much shorter than the spikes, the lowest long-sheathing, spathaceous, strongly purple-tinged and white-hyaline-margined; scales ovate, acutish, smooth, rather longer and wider than the perigynia, dark-purplish with strongly developed hyaline margins, the midvein lighter-colored; perigynia obovoid, obscurely triangular, not inflated, 2.5-3 mm. long, 1.5 mm. wide, membranaceous, straw-colored, or light-brownish above, appressedpubescent, 2-keeled, otherwise nerveless or very obscurely nerved, short-stipitate, tapering at base, rounded at apex and abruptly minutely beaked, the beak about 0.5 mm, long, the orifice hyaline, obliquely cut; achenes oblong-obovoid, brownish, shining, sharply triangular, with convex sides above, closely enveloped, 1.5-2 mm. long, 1-1.25 mm. wide, short-conic-apiculate and jointed with the straight slender style; style short-exserted ; stigmas three, long, blackish.
TvPE uiCM.nv : Woo<led country, latitude 54°-64° north, northwest America. Norway and Cumberland House, according to Boott (in Hook. Fl. Bor. Am. 2: 223).
Distributio.v: Dry soil in open sunny places, western New York and Ontario to Alberta, and southward to Illinois and South Dakota; rare and local eastward. (Specimens examined from western New York. Ontario, Michigan, northwestern Indiana, Illinois, Wisconsin, Minnesota, South Dakota, Manitoba, Iowa, Saskatchewan, Alberta.)