Thick Head Sedge

Carex pachystachya Cham.; Steud. Syn. Cyp. 197. 1855
Carex /estiva var. pachystachya L. H. Bailey, Mem. Torrey Club 1: 51. 1889. (Based on C. pachystachya Cham.)
Carex maclmiana var . pachystachya "I,. H. Bailey" Kukcntli. in ICnglcr, Pflanzenreich 4 M : 197. 1909. (Based on C. pachystachya Cham.)
Very densely cespitose, the rootstocks very short, blackish, fibrillose, the culms 3-10 dm. high, slender, 2.5-3.5 mm. thick at base, conspicuously striate, obtusely triangular below, sharply so above, much exceeding the leaves, smooth or slightly rough beneath the head, bfOm at base, and clothed with the dried-up leaves of the previous year, the lower bladeless; leaves with well-developed blades usually 3-5 to a fertile culm, all on the lower third, but not bunched, the blades flat, deep-green, not stiff, 1-3 dm. long, 2-4 mm. wide, roughened towards the apex, the sheaths tight, white-hyaline ventrally, thin at mouth and prolonged beyond ; blade and continuous with ligule; spikes 4-12, gynaecandrous, closi I ited into
e suborbicular or oblong head 1-2.5 cm. long, 7 IS mm. thick, the individual spikes
icular or short-oblong, 5 B mm. long, i 6 nun. wide, round-truncate at base, obti apex, the upper hardly distinguishable, tinstaminate flowen Incori plcuous, thi pa lo JO, ascending oi Dreading, with conspicuou call like, oi the lowest short-awned, much shorter than head; scales ovate, acute, chestnut-brown or blackish, with gTeenish or yellowish midrib, scarcely hyaline-margined, about the width of the perigynia below, but exceeded by their beaks; perigynia plano-convex, ovate, thick, 3.5-5 mm. long, 1.5-2.25 mm. w T ide, submembranaceous but firm, copper-colored at maturity, narrowly wingmargined to base, serrulate to middle, nerveless ventrally, several-nerved dorsally, rounded at base, tapering somewhat abruptly into a beak not half the length of the body, serrulate, obliquely cut dorsally, chestnut-browntipped, bidentulate, the tip terete, smooth, slightly hyaline; achenes lenticular, short-oblong, 1.5 mm. long, O.S mm. wide, substipitate, apiculate; style slender, straight, jointed with achene, deciduous; stigmas two, slender, yellowish-brown.
Type locality: "In Unalaschka."
Distribution: Wyoming to California, and northward to Alberta and British Columbia, and along the Alaskan coast to the Aleutian Islands. (Specimens examined from Wyoming, Montana, Alberta, Idaho, California. Oregon, Washington. British Columbia (including Vancouver Island), Alaska )
Iu.i strations: Abrams. 111. Fl. Pacif. St. /. 744: Am. Jour. Sci. IV. 18: 16. /. /, 2. 5 (as C. f estiva).
Carez pachystachya var. gracilis (Olney). Carex f estiva var. gracilis Olney; A. Gray, Proc Am. Acad. 8: 407, name only. 1872. (Based on Hall 586 from Oregon.) Carex festiva var. gracilis Olney ; W. Boott, in S. Wats. Bot. Calif. 2: 234. 1SS0. (Excluding specimens cited.) Carex mullimoda L. H. Bailey. Bot. Gaz. 21: 5. 1896. (Based on C. festiva var. gracilis Olney.) Carex maclmiana var. gracilis "Olney" Kukenth. in Engler. Pflanzenreich 4 20 : 197. 1909. (Based on C. festiva var. gracilis Olney.) Carex ol mpica Mackenzie. Bull. Torrey Club 43 : 610. 1917. (Type from Washington.) More slender; leaf-blades 1-2 mm. wide, light-green; inflorescence of 3-6 spikes aggregated or in a head more or less interrupted below; spikes with 8-15 ascending or in age more or less spreading perigynia. Type locality (of C. festiva var. gracilis Olney, on which this variety is based): Oregon (Hall 586). Distribution: Dry soil, mostly at lower elevations, from northern California to British Columbia and Idaho. (Specimens examined from California, Oregon, Washington, British Columbia, Idaho.)

Carex pachystachya is a species of sedge known by the common name Chamisso sedge.

It is native to western North America from Alaska to Saskatchewan to California. It grows in dry to wet areas in many types of forest and grassland habitat.