Shaved Sedge

Plants densely to loosely cespitose; rhizomes ascending to erect, brown to reddish brown, 0–10 mm, stout. Culms 4–16 cm, scabrous distally; bases (remnants of old leaves) fibrous. Leaf blades pale to bright green, equaling or exceeding stems, 0.5–4.3 mm wide, herbaceous or coriaceous, glabrous abaxially, strongly scabrous to papillose adaxially. Inflorescences with both staminate and pistillate scales; peduncles of basal pistillate spikes erect, short to elongate, stout to slender; peduncles of staminate spikes 0.8–15 mm; proximal nonbasal bracts scalelike, shorter than inflorescences. Spikes: proximal pistillate spikes 2–3 (basal spikes 1–2); cauline spikes usually overlapping with staminate spikes, with 3–10(–15) perigynia; staminate spikes 4.5–11.3 × 1.1–3 mm. Scales: pistillate scales pale brown to reddish brown, with narrow white margins, ovate, 2.9–4.1 × 1.5–1.9 mm, equaling or exceeding perigynia, apex acute to long-acuminate; staminate scales ovate, 4.2–5.4 × 1.2–2.1 mm, apex obtuse or acute to acuminate. Anthers 1.6–2.9 mm. Perigynia green to pale brown, veinless, ellipsoid, obtusely trigonous in cross section, 3.1–4.7 × 1.1–1.6 mm; beak straight, pale green, occasionally with reddish brown tinge near apex, strongly 2-edged, 0.9–2 mm, smooth or ciliate-serrulate, apical teeth 0.2–0.5 mm. Stigmas 3. Achenes brown, ellipsoid to obovoid, obtusely trigonous in cross section, 1.6–2 × 1.2–1.6 mm.

Carex umbellata Schkuhr ex Willdenow var. tonsa Fernald, Proc. Amer. Acad. Arts 37: 507. 1902; C. rugosperma Mackenzie var. tonsa (Fernald) E. G. Voss

Carex tonsa (Fernald) Bickn. Bull. Torrey Club
35:492. 1908.
"Carex umbellala Schk." Boott, 111. Carex 98, in part. pi. 293. I860.
Carex umbellala var. lonsa Fernald, Proc. Am. Acad. 37: 507. 1902. (Type as given below.) Carex umbellala f. lonsa "Fernald" Kiikenth, in Engler, Pflanzenreich 4-'>: 453. 1909. (Based on C umbellala var. tonsa Fernald.)
Loosely cespitose, from stoutish, tough, branching rootstocks, the stolons short-ascending, the culms 2-15 cm. high, much exceeded by the leaves, sharply triangular, slender but stiff, strongly roughened, strongly reddish-brown-tinged and fibrillose at base, phyllopodic; sterile culms aphyllopodic, the sheaths little filamentose; leaves numerous and conspicuous, the blades spreading at maturity, deep-green, thick, stiff, firm, 5-25 cm. long, 2-4.5 mm. wide, channeled especially towards the base, the margins revolute, long-attenuate, very rough towards the apex : sheaths smooth dorsally, but little or not at all breaking or filamentose ventrally. the ligule much wider than long; staminate spike 6-12 mm. long, 2-3 mm. wide, the scales obovate, acute, reddish-brown with greenish or straw-colored 3-nerved center and whitehyaline margin; a pistillate spike occasionally present at base of the staminate spike, sessile or nearly so, erect-ascending; basal pistillate spikes 2-3, on long slender peduncles, shortoblong, 6-10 mm. long, 4.5-6 mm. wide, densely flowered, the perig>'nia 3-20, appressedasccnding, in several rows; bract at base of non-basal spike setaceous, not sheathing, sparingly reddish-tinged at base, from much shorter than to slightly exceeding spike; scales conspicuous, ovate, short-cuspidate to acute, wider and from slightly shorter to slightly longer than perigynia, whitish or straw-colored with 3-nerved green center, the upper often purplish-browntinged; perigynia 3.5-4.5 mm. long, the body broadly oval, 1.75-2 mm. long, 1.25-1.5 mm wide, compressed-orbicular and obscurely triangular in cross-section, 2-keeled, otherwise nerveless or more or less nerved towards base, subcoriaceous, light-green, at most very sparsely short-pubescent above and on the ciliate-serrulate beak, stipitate, tapering into a base 0.75 mm. long, contracted into a beak 1.75-2.5 mm. long, strongly 2-edged, bidentate; achenes orbicularobovoid, triangular with convex sides and sharp and narrow angles, closely enveloped, brownish, shining, pitted, the superficial cells inconspicuous, substipitate, 1.75-2 mm. long, triincate at apex and minutely apiculate, jointed with the straight, slender style; stigmas three, slender.
Type locality (of C. umbellata var. (onsa, on which C. lonsa is based): Hebron, Maine (Allen); North Stonington, Conn. (Graves).
Distribution: Dry sterile fields and dry open woods. Nova Scotia and Quebec to Minnesota and Alberta, and southward to the District of Columbia and Indiana. (Specimens examined from Prince Edward Island, Nova Scotia, Quebec, Elaine, Massachusetts, Rhode Island. Connecticut, New York, New Jersey. Pennsylvania, Delaware. Maryland, District of Columbia. Ontario. Michigan, Wisconsin, Indiana, Minnesota, Alberta.)

Carex tonsa, also known as shaved sedge, is a species of flowering plant in the sedge family, Cyperaceae. It is native to Canada and the Eastern United States.