Carex tonsa (Fernald) E.P. Bicknell - Shaved Sedge


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Carex tonsa - (image 1 of 6)



Family: Cyperaceae


Section Acrocystis     


Fields, dunes, open woods and woodland edges, ridges, in dry, sandy or rocky, usually acidic soils.




Newfoundland to WI and IL (also Saskatchewan, Alberta, and British Columbia), south to NJ, MD, and VA.


Loosely to densely tufted perennial; stems basally fibrillose, 4-16 cm, much surpassed and often concealed by the leaves; leaves 0.5-4.3 mm wide; staminate spike terminal, 4.5-11.3 mm, sometimes with a short pistillate spike just beneath it, the subtending bracts of this pistillate spike scale-like and shorter than the staminate spike; 1-2 near-basal, short-pedunculate pistillate spikes 4-10 mm with 3-10(-15) perigynia, generally associated with each flowering stem, more or less removed from the terminal staminate spike; pistillate scales brown to reddish brown with narrow white margins, ovate, 2.9-4.1 mm long, equaling or exceeding the perigynia, acute to long-acuminate at the apex; perigynia 3.1-4.7 mm long, pale green maturing to pale brown, veinless, ellipsoid, obtusely trigonous; beak straight, pale green, strongly 2-edged, 0.9-2 mm, smooth or ciliate-serrulate, with apical teeth 0.2-0.5 mm; achenes brown, ellipsoid to obovoid, obtusely trigonous, 1.6-2 mm.


Fruiting mid April to June

Wetland indicator: NA

Seeds are dispersed by ants. Similar to C. umbellata but with longer perigynia (3.1-4.7 mm long vs. 2.2-3.2 mm long) with longer beaks (0.9-2 mm vs. 0.4-1 mm).

The plants pictured here are var. rugosperma (Mack.) Crins with relatively long, thin, flexuous leaves and pubescent perigynia. Typical C. tonsa has relatively short, thick, and rigid leaves and mostly glabrous perigynia save for a few hairs near the base of the beak.


Ball, P.W. and A.A. Reznicek. 2002. Carex, In: Flora of North America Editorial Committee, Eds. Flora of North America North of Mexico. Volume 23. Oxford University Press, New York.


Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Ed.
The New York Botanical Garden. Bronx, NY




Michael Hough 2018