Plants without conspicuous rhizomes. Culms 25-90 cm, 1.6-2 mm wide basally, 0.6-0.7 mm wide distally. Leaves: sheaths tight, green, fronts hyaline; ligules less than 2 mm, as long as wide; widest leaf blades 1.5-2.5(-3) mm wide. Inflorescences with 4-10 spikes, 1.5-3.5 cm × 6-10 mm; proximal internodes as long as to slightly longer than proximal spikes, rarely 2 times as long; proximal bracts to 3 cm; spikes with 3-10 ascending to spreading perigynia. Pistillate scales brown with green, 3-veined center, ovate, 3.4-4 × 1.6-2 mm, body wider than and as long as perigynium, apex acuminate to short-awned, awn less than 1 mm. Anthers 2.5 mm. Perigynia brown, sometimes with green margins, faces obscurely veined, 2.5-4.5 × 1.5-1.9 mm, base of body somewhat spongy, margins serrulate distally; beak 0.6-1.3 mm, apical teeth 0.2-0.3 mm. Stigmas straight, 0.07 mm wide. Achenes elliptic-circular, 1.9-2 × 1.5-1.6 mm.
There are questionable records from central Mexico of Carex occidentalis, which is otherwise endemic to the flora area.
FNA 2002, Cronquist et al. 1977
Common Name: western sedge Duration: Perennial Nativity: Native Lifeform: Graminoid General: Densely clustered with sometimes inconspicuous but short and freely rooting rhizomes, stems 25-90 cm, 1.6-2 mm wide at the base, 0.5-0.7 mm at tip. Vegetative: Leaves with tight green sheaths, shorter than stems, flat or nearly so, 1-2.5 mm wide, borne on lower part of stem, generally not clustered, ligules less than 2 mm, as long as wide. Inflorescence: Several, small, few-flowered, sessile spikes, rather loosely aggregated into a slender, oblong-cylindric head, 1.5-3.5 cm long by 6-10 mm wide, composed of 4-10 spike, irregular or interrupted especially toward the base, lower spikes readily visible; sheathless bracts to 3 cm, spikes with 3-10 ascending to spreading perigynia; pistillate scales greenish straw colored to coppery brown, ovate, 3.4-4 mm long by 1.6-2 mm wide, about equaling or surpassing the perigynia, acuminate or shortly awn tipped to 1 mm; perigynia brown, sometimes with green margins, 2.5-4.5 mm long by 1.5-2 mm wide, base of body spongy, margins serrulate near tip, beak 0.6-1.3 mm, apical teeth 0.2-0.3 mm; achenes elliptic-circular, 2 mm long by 1.5 mm wide. Ecology: Found on open to wooded slopes often in dry sites from 4,000-11,000 ft (1219-3353 m); flowers April-July. Notes: This is one of the most common and widespread sedges in Arizona, and is most likely confused with Carex vallicola. Both have moderately elongate inflorescences with androgynous spikes and plano-convex perigynia, and prefer dry forest habitats over riparian. However, in Carex occidentalis, the perigynia are more regularly arranged in the spikes in an ascending pattern, while in C. vallicola they are more irregularly spreading, giving the inflorescence a more -confused- texture. The pistillate scales are usually as long as the perigynia in C. occidentalis, and are distinctly shorter in C. vallicola, which causes the perigynia to be more exposed. Both species are cespitose, unlike Carex siccata, another sedge with a relatively narrow and moderately elongate inflorescence, which is always distinctly rhizomatous (see notes under C. siccata for further distinctions). All three of these species prefer dryer meadows and forests, though they can occasionally be found on the periphery of riparian zones. (Notes: Max Licher and Glenn Rink 2012) Ethnobotany: Unknown Etymology: Carex is the classical Latin name for the genus, while occidentalis means of the west. Synonyms: Carex neomexicana Editor: SBuckley, 2010