Carex petricosa Dewey

Carex petricosa shows considerable variation, even within one clone, in the distribution of staminate and pistillate flowers in the inflorescence. The two taxa recognized can usually be distinguished by stigma number. A small number of individuals are to determine on purely morphologic grounds.

Plants loosely cespitose; rhizomes slender, long. Culms 10–90 cm. Leaves: blades 1–3.5 mm wide. Inflorescences 3–12(–22) cm; proximal internodes 10–60(–100) mm; peduncles of proximal spikes to 8 cm; proximal bracts with blades 5–140 mm, sheaths cylindric, 5–25(–35) mm, mouth 0.9–1.5 mm wide. Spikes 3–8; lateral spikes androgynous or pistillate, rarely some entirely staminate, the proximal inclined or pendent, 5–30 × 3–7 mm; terminal spike staminate or androgynous, 10–28 × 1.8–4 mm. Pistillate scales brown to black, oblong-obovate, 3–5.8 × 1.1–2 mm, apex obtuse to acute, sometimes shortly awned. Staminate scales brown or black with hyaline margins, oblong-ovate, 3.1–6.2 × 1–3 mm. Anthers 1.5–3 mm. Perigynia ascending, pale yellow proximally, brown or black distally, 3–9-veined, lanceolate, 3.5–5.5 × 1.1–2.4 mm, margins ciliate-serrulate distally, apex tapered, shortly setose, sometimes setae confined to veins, or subglabrous; beak indistinct, to 0.5(–1) mm. Achenes obovoid, 1.7–2.2 × 1–1.3 mm.

Carex petricosa Dewey, Am. Jour. Sci. 29: 246 pi. W,f. 70. 1836. Loosely cespitose and slenderly long-stoloniferous, the stolons horizontal, the clumps small, the culms 1.5-2.5 dm. high, slender, stiffish, phyllopodic, obtusely triangular, smooth, slightly fibrillose at base, the dried-up leaves of the previous year conspicuous, their sheaths strongly striate; leaves with well-developed blades 6-12 to a fertile culm, clustered above the base, the blades light-green, stiff, usually 7-15 cm. long, 2-2.5 mm. wide, flat or somewhat channeled toward base, roughened toward the long-attenuate apex, the sheaths tight, concave or truncate at mouth, yellowish-tinged and red-dotted ventrally, the ligule very short; terminal spike androgynous, short-peduncled, about 18 mm. long, usually 3.5-5 mm. wide, the scales oblong-obovate, acute or slightly cuspidate, purplish-black with broad lighter midrib and strongly developed white-hyaline margins; pistillate spikes 2 or 3, the upper approximate, the lowest separated, erect, the upper short-peduncled or nearly sessile, the lower on peduncles 1-2 times their own length, narrowly oblong, 8-15 mm. long, 4 mm. wide, little attenuate at apex, closely flowered, containing 8-20 appressed perigynia in few rows; lowest bract leafletlike, with sheath about 1 cm. long, exceeded by inflorescence; upper bracts reduced; scales oblong-obovate, obtuse or acutish, rounded on back and slightly ciliate, purplish-black with lighter center, hyaline toward apex, wider than but exceeded by mature perigynia; immature perigynia lanceolate, 4-5 mm. long, 1.5 mm. wide, strongly flattened, not inflated, minutely hispidulous, ciliate on margins, thin, membranaceous, straw-colored at base, purplish-blacktinged above, finely nerved, rounded at base and short-stipitate, tapering at apex, beakless or very nearly so, the apex white-hyaline, obliquely cleft, becoming bidentulate; achenes triangular; stigmas 3, slender, blackish.
Type locality: "Found on the summit of the Rocky Mountains" (Drummond), probably about 59° lat.
Distribution : Mountains, British Columbia and Alberta. (Specimens examined from Alberta.)

Carex petricosa adalah spesies tumbuhan seperti rumput yang tergolong ke dalam famili Cyperaceae. Spesies ini juga merupakan bagian dari ordo Poales. Spesies Carex petricosa sendiri merupakan bagian dari genus Carex. Nama ilmiah dari spesies ini pertama kali diterbitkan oleh Dewey.

Carex petricosa là một loài thực vật có hoa trong họ Cói. Loài này được Dewey mô tả khoa học đầu tiên năm 1836.