15. Rhynchospora macra (C. B. Clarke ex Britton) Small, Man. S.E. Fl. 180. 1933 (as Rynchospora).
Rhynchospora alba (Linnaeus) Vahl var. macra C. B. Clarke ex Britton, Trans. New York Acad. Sci. 11: 88. 1892 (as Rynchospora); Phaeocephalum album (Linnaeus) House var. macrum (C. B. Clarke ex Britton) Farwell; Triodon albus Farwell var. macer (C. B. Clarke ex Britton) Farwell
Plants perennial, cespitose, 40–80 cm; rhizomes absent. Culms erect, trigonous, multiribbed, rather stiff. Principal leaves overtopped by culm; blades narrowly linear, proximally flat, (1.5–)2–3.5 mm wide, apex tapering, trigonous. Inflorescences: spikelet clusters 1–3, turbinate to hemispheric, 1.5–3 cm wide; subtending leafy bracts mostly exceeded by distal compound. Spikelets pale brown to nearly white, fusiform, 4–5(–7) mm, apex narrowly acute; fertile scales elliptic, 3.5–4 mm, apex narrowly acute, midrib excurrent as mucro. Flowers: perianth bristles (15–)18–20, reaching tubercle tip, retrorsely barbellate. Fruits 1 per spikelet, 2.5–3.2 mm; body brown with pale center, obovoid distal to short stipe, lenticular, 1.7–2.2 × 0.8–1.5, margins narrow, wirelike, flowing into tubercle edges; tubercle flat, narrowly triangular-subulate, 0.8–1 mm.
Fruiting late summer–fall. Sands and sandy peats of savanna bogs and seeps, pinelands; 0–200 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex.; Central America (Nicaragua).