Thurber's Sedge

Plants densely to loosely cespitose; rhizomes short, no more than 10 cm. Culms trigonous in cross section, 40–100 cm, scabrous-angled distally. Leaves: basal sheaths reddish purple; ligules longer than wide; blades pale to mid green, flat to W-shaped, 3.5–9 mm wide, glabrous. Inflorescences 6–25 cm; proximal bract 15–40 cm, exceeding inflorescence; proximal 3–4 spikes pistillate, erect or the proximal spreading; terminal 1–2 spikes staminate. Pistillate scales ovate, obtuse to acuminate, 2–4.4(–5.1) × 0.7–1.3 mm, shorter than perigynia, margins erose, apex contracted, scabrous-awned, awn mostly shorter than body. Staminate scales scabrous-awned, sometimes also ciliate-margined. Perigynia ascending, ca. 13–25-veined, veins separated by 3+ times their width, confluent at or proximal to mid beak (except for 2 prominent lateral), narrowly elliptic, 3.1–4.8 × 0.9–1.5(–1.8) mm, herbaceous, apex tapered; beak 0.9–1.8 mm, smooth, bidentulate, teeth straight, 0.4–0.9 mm. Stigmas 3. Achenes yellow to pale brown, trigonous, smooth.

Ariz.; Mexico.

Fruiting May–Aug.

Stream banks, springheads, seeps, wet meadows; 1100–1800m.

Carex thurberi Dewey, in Torr. Bot. Mex. Bound. Surv. 232. 1859
"Carex acutata Boott" W. Boott, Bot. Gaz. 9: 92. 1884.
Carex hystricina var. angustior L. H. Bailey; Rose, Contr. U. S. Nat. Herb. 1: 126. 1891. (Type
from Willow Springs, Arizona.) Carex hystricina f. L. H. Bailey; Rose, Contr. U. S. Nat. Herb. 1 : 126. 1891. (Same type; accidental
repetition in list.) Carex arizonensis Kiikenth. Bot. Jahrb. 27: 549. 1899. (Type from Arizona.)
Cespitose and with a few slender horizontal stolons, the rootstocks stout, the clumps apparently large, the culms 6-12 dm. high, stoutish, erect, exceeded by leaves and very much by the bracts, phyllopodic, sharply triangular, smooth or roughish above, strongly purplishred-tinged at base, the lower sheaths breaking and becoming somewhat filamentose; leaves with well-developed blades 5-10 to a fertile culm, obscurely septate-nodulose, not bunched, the blades flat with revolute margins, thin but stiffish, light-green, 2-5 dm. long, 4-8 mm. wide, very rough toward apex, long-attenuate, the sheaths sparsely hispidulous dorsally, whitehyaline ventrally, concave and short-hispid at mouth, the ligule short, much wider than long; terminal spike staminate, erect, short-peduncled, linear, 4-8 cm. long, 3-5 mm. wide, the scales oblong-obovate, abruptly rough-awned, white-hyaline and slightly reddish-tinged, with 3nerved, appressed-hairy, green center; pistillate spikes 3 or 4, approximate or more or less separate, drooping or the upper weakly erect on rough slender peduncles shorter than or the lowest often longer than the spikes, the latter oblong-cylindric or cylindric, 3.5-7 cm. long, 8-10 mm. wide, densely flowered, containing 50-100 ascending or spreading-ascending perigynia in several to many rows; bracts leaf-like, sheathless or very nearly so, very strongly exceeding inflorescence; scales ovate, often emarginate, strongly rough-awned, the body, large, ciliate-serrulate above, hyaline and slightly reddish-brown-tinged, with 3-nerved green center; nearly as wide as but much shorter than the perigynia; perigynia elliptic-ovoid, 4-5 mm. long, 1.5 mm. wide, slightly inflated, suborbicular (obscurely triangular) in cross-section, submembranaceous, puncticulate, yellowish-green, finely several-ribbed, rounded at base, short-stipitate, tapering into a smooth, strongly bidentate beak 1.5 mm. long, the teeth slender, stiff, whitish, slightly spreading, 0.5-0.75 mm. long; achenes oblong-obovoid, 1.75 mm. long, 0.75 mm. wide, triangular with blunt angles, loosely enveloped, substipitate, continuous with and tipped by the slender, abruptly bent, persistent style; stigmas 3, blackish, short, slender.
Type locality: "Mabibi, Sonora, June; Thurber."
Distribution: Swampy soil, Guatemala to Arizona; Santo Domingo. (Specimens examined from Arizona, Chihuahua, Sonora, Vera Cruz, Guatemala, Santo Domingo.)