Culms to 400 cm × 4 mm, scabrous. Leaves: sheath fronts spotted red-brown, plane, apex truncate or concave; ligule rounded, to 1 mm, free limb to 0.2 mm; blades 15 cm × 5 mm, shorter than flowering stem. Inflorescences loosely paniculate, 4-10 cm × 7-15 mm, the proximal branches distinctly separate; bracts scalelike, dilated with wide hyaline edges and prominent midvein; the proximal bracts setaceous, prolonged to 10-15 mm. Scales hyaline, pale brown with prominent white-hyaline margins, apex acute or obtuse. Perigynia yellow-brown to dark brown, 5-11-veined abaxially, occasionally 3-5-veined adaxially, body ovate, 3-3.6 × 1.2-1.6 mm, base rounded or cordate, conspicuous corky tissue distending the perigynium; beak chestnut brown, 0.6-1.5 mm, apex white-hyaline, deeply bidentate. Achenes brown, ovate, 1.5 × 1 mm.
Fruiting Jun-Jul. Stream banks, springs, seeps; 1000-3000 m; Ariz.; Mexico (Chihuhua).
Carex chihuahuensis is distinguished from the similar C. alma by the pale brown perigynia and the short-prolonged bracts; there is overlap in some character states. The relationship between these species merits further study, as does their placement in sect. Multiflorae because their achene and perigynium characteristics approach those of sect. Vulpinae.
Common Name: Chihuahuan sedge Duration: Perennial Nativity: Native Lifeform: Graminoid General: Tufted perennial with stems to 40 cm, 4 mm wide, scabrous. Vegetative: Leaf sheaths spotted red-brown, plane, with a truncate to concave apex, ligule rounded to 1 mm, leaf blades 15 cm long by 5 mm wide, shorter than flowering stem. Inflorescence: Loosely paniculate, 4-10 cm by 7-15 mm, the lower branches distinctly separate, bracts scalelike, dilated with wide hyaline edges and prominent midvein, the lower bracts setaceous, prolonged to 10-15 mm, scales hyaline, pale brown with prominent white-hyaline margins, apex acute or obtuse, perigynia yellow brown to dark brown, 5-11 veined below, ovate body, 3-3.6 mm long by 1.2-1.6 mm wide, base rounded or cordate, conspicuous corky tissue distending the perigynium, the beak chestnut brown, 0.6-1.5 mm; achenes brown, ovate, 1.5-1 mm. Ecology: Found along stream banks and at seeps and springs from 3,500-10,000 ft (1067-3048 m); flowers June-July. Distribution: se AZ; sw NM; n MEX. Notes: This species is most closely related to Carex alma, a more robust plant that has dark brown perigynia when mature, compared to the lighter brown of C. chihuahuensis. Intermediates between the two species can often be found. While usually cespitose, Carex chihuahuensis can also exhibit a short rhizomatous habit with dark bases, getting it confused with C. praegracilis (which also occasionally has a few paniculate lower branches to its inflorescence). In Carex praegracilis, the inflorescences are most often predominantly unisexual with sometimes a few flowers of the opposite sex, while in C. chihuahuensis, each of the spikes is typically androgynous. (Notes: Max Licher and Glenn Rink 2012) Ethnobotany: Unknown Etymology: Carex is the classical Latin name for the genus, while chihuahuensis means of or from Chihuahua. Synonyms: None Editor: SBuckley 2010, FSCoburn 2015