Rhynchospora debilis

Plants perennial, cespitose, 20-45 cm; rhizomes absent. Culms erect to arching or spreading, leafy, ± filiform, ± terete, stiff to rather lax. Leaves exceeded by culm; blades linear filiform, proximally shallowly concave, 1 mm, apex tapering, trigonous, blunt or broadly acute. Inflorescences: spikelet clusters 1-2, mostly compact, turbinate to hemispheric; leafy bracts setaceous, exceeding spikelet clusters. Spikelets dark red brown, ovoid, 2-3 mm, apex acute; fertile scales obovate, 1.5-1.7(-2) mm, apex broadly rounded or retuse, midrib excurrent as cusp or mucro to 0.5 mm. Flowers: bristles 6 or vestigial, rarely reaching fruit midbody, antrorsely barbellate. Fruits 1-2 per spikelet,1.7-2 mm; body brown with large pale center, lenticular, broadly obovoid to ± orbicular, 1.2-1.5 × 1.4-1.6 mm; tubercle flat, triangular, concave-sided, 0.4-0.6 mm, sometimes apiculate.

Fruiting late spring-fall. Sands and peats in low, open fields, bogs, seeps, low pinelands, savannas, and ditch banks; 0-200 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex., Va.

Rhynchospora debilis is very similar to R. wrightiana except it has smaller spikelet clusters and more depressed fruit tubercles. It is a common invader of cutover and bulldozed low pineland where it assumes a low spreading habit, its many culms radiating from the common center much like spokes in a wheel.

Much like no. 19 [Rhynchospora fascicularis (Michx.) Vahl], but the stems slender and lax, no more than 1 mm thick; longer lvs equaling the stems; bristles never more than half as long as the achene. Coastal plain from se. Va. to n. Fla. and Ala.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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