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FNA | Family List | FNA Vol. 23 | Cyperaceae | Carex

264. Carex laxiflora Lamarck in J. Lamarck et al., Encycl. 3: 392. 1792.

Carex laxiflore

Carex laxiflora var. serrulata F. J. Hermann

Culms densely tufted, lateral or central, ascending or lax to decumbent, 39–47 cm × 0.8–2 mm. Leaves: basal sheaths light brown; sheaths 6–22 mm; blades ascending, midrib and 2 lateral veins developed, occasionally slightly corrugated, 19–25 cm × 5–26 mm, blades of overwintering leaves smooth or, rarely, sparsely papillose abaxially. Inflorescences: peduncles of proximal spikes erect, 0–3.4 cm, of lateral spikes 1.4–3.3(–5.3) times as long as spikes they subtend; of terminal spikes 1–2.2 cm. Bracts 7.2–17.5 cm × 2–8 mm, bract blade of distal lateral spikes linear, narrower than spikes, widest bract blade of distalmost lateral spike 0.5–3.4 mm wide. Spikes (3–)4 per culm; lateral spikes 9–33 × 3.2–4 mm; terminal spike linear to clavate, 23–24(–34) × 1.5–3 mm. Pistillate scales 2.5–3 × 1.2–1.5 mm, apex acute or apiculate. Staminate scales 3–3.5 × 1–1.5 mm, oblong-ovate, margins white-hyaline or brownish, apex obtuse or acute. Anthers 2.6–3 mm. Perigynia 3–20 per spike, usually separate, ratio of longer lateral spike length to perigynia number 1.9–3.4, ascending, conspicuously (22–)25–32-veined, (2.6–)3.2–4.1(–4.6) × 1.2–1.6 mm; beak straight, 0.5–1.4 mm. Achenes broadly ellipsoid, 1.8–2.2(–3.4) × 1–1.4 mm. 2n = 40.

Fruiting spring–early summer. Dry or moist, deciduous or mixed deciduous-evergreen forests, higher elevations southward; 0–1000 m; N.S., Ont., Que.; Ala., Ark., Conn., Del., Ga., Ill., Ind., Ky., Maine, Md., Mass., Mich., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., Tenn., Vt., Va., W.Va., Wis.

The Carex laxiflora complex contains a wide array of phenotypic variation and deserves further research. F. J. Hermann (1938) proposed the name C. laxiflora var. serrulata; however, among the numerous specimens of C. laxiflora we studied, the key characteristic of ciliate-serrulate bract-sheaths varied greatly.


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