Wolf's Spike Rush

Eleocharis wolfii is presumably extirpated from Colorado, Kansas, New York (Long Island), and Ohio. It was recently rediscovered in Wisconsin. Some literature reports (e.g. from the Great Plains) are based on misidentified specimens. I have not seen specimens to verify literature reports from Alberta, Saskatchewan, Colorado, Missouri, and Nebraska.

Plants perennial, often forming large mats; rhizomes 0.25–0.6 mm thick, internodes 1–4 cm, scales 2 mm. Culms sometimes decumbent, in same plant sides variably smooth or with 1 to few acute ridges (often nearly smooth or with 1 ridge on 1 side and several ridges on the other), greatly compressed, usually inrolled when dry, rectangular in cross section, 10–40 cm × 0.3–1.5 mm, 0.2–0.5 mm thick, firm, margins often sharply acute, margins and often 1 or more ridges minutely serrulate at 20–30X. Leaves: distal leaf sheaths persistent, red proximally, colorless or stramineous or whitish distally, slightly inflated, thickly membranous, apex acute. Spikelets ovoid or lanceoloid, 3–9 × 1.5–2.5 mm, apex acute; floral scales 15–30, 6 per mm of rachilla, orange-brown or often stramineous or colorless, midrib region stramineous or greenish, ovate-lanceolate, (2.2–)2.7–3.2 × 1.5 mm, midrib prominent, apex acute. Flowers: perianth bristles absent; anthers 1.1–1.75 mm. Achenes compressed-trigonous, with angles plus longitudinal ridges ca. 9–13, prominent, obovoid, mostly 2 times longer than wide, 0.7–0.9(–1.1) × (0.4–)0.5 mm, trabeculae 30–60, rather obscure and crowded. Tubercles brownish, pyramidal, usually depressed, 0.1–0.15 × 0.2–0.25 mm.

Ala., Ark., Colo., Ill., Ind., Iowa, Kans., La., Minn., Miss., Mo., N.Y., N.Dak., Ohio, Okla., Tenn., Tex., Wis.

Fruiting late spring–early summer (May–Jun).

Ephemeral pools in open grasslands, oak woodlands on river terraces, limestone barrens; 10–500m.

Scirpus wolfii A. Gray, Proc. Amer. Acad. Arts 10: 77. 1874

Eleocharis wolfii A. Gray in H. Patters Cat. PI. Illinois 46. 1876.
Scirpus Wolfii A. Gray, Proc. Am. Acad. 10 : 77. 1874.
Culms sparsely cespitose, from slender creeping rhizomes, 1.5-3 dm. high, about 1 mm. in diameter, two-edged, often concavo-convex or inrolled, frequently spiral, lightly striate ; sheath oblique and scarious at the apex ; spikelets slender-ovoid, acute, 5-9 mm. long ; scales oblong-ovate, acuminate, purple-striate, with a scarious margin ; style trifid ; anthers 3, 1 mm. long; achene pyriform, light brown, shining, 1 mm. long, strongly costulate with 9 longitudinal ribs and about 40-45 trabeculae in each longitudinal series; style-base depressedtruncate, with an apiculate center; bristles lacking.
Type locality: Canton, Illinois (/. Wolf).
Distribution: Wet meadows and prairies: New York (adventive), Indiana, Tennessee, Illinois, Louisiana, Iowa, Missouri, Oklahoma, Kansas, Colorado, Saskatchewan.