Rhynchospora cephalantha A. Gray

North American plants referred to Rhynchospora axillaris (Lamarck) Britton [Phaeocephala axillare (Lamarck) House by N. L. Britton and A. Brown (1913) and J. K. Small (1933)] are actually R. cephalantha. A photograph of the type specimen of Schoenus axillaris Lamarck (from P) reveals what appears to be an immature top of S. glomeratus [R. glomerata (Linnaeus) Vahl].

Plants perennial, cespitose, 40–100(–150) cm; rhizomes absent. Culms arching, leafy, obscurely and convexly trigonous, multi-ribbed, slender to stoutish. Principal leaves overtopped by culm; blades linear, flat proximally, 1.5–3 mm wide, apex tapering, trigonous. Inflorescences: spikelet clusters 3–several, widely spaced, often equidistant, mostly hemispheric to globose, occasionally lobed, 1–2 cm thick; bracteal leaves much exceeding subtended inflorescence. Spikelets dark red-brown to dark brown, lance ellipsoid to ellipsoid, 4–5(–6) mm, apex acute; fertile scales elliptic, 3–3.5(–4.5) mm, apex acute, midribs 3, laterals indistinct. Flowers: perianth bristles 6, reaching tubercle tip, retrorsely (rarely antrorsely) barbellate. Fruits 1(–2) per spikelet, 3.5–4(–4.2) mm; body brown with pale center, obovoid distal to stipe, lenticular, 2–2.3 × 1–1.5(–2) mm; tubercle triangular-subulate, (1–)1.5–2 mm, at least 0.5 mm wide at base.

Ala., Del., Fla., Ga., La., Md., Miss., N.J., N.Y., N.C., S.C., Tex., Va.

Fruiting summer–fall.

Sandy silts, sands, and peats of shores, boggy streams, seeps, savannas, and savanna bogs; 0–200m.

Rhynchospora cephalantha var. attenuata Gale; R. cephalantha var. pleiocephala Fernald & Gale

Rhynchospora cephalantha, known by the common name of bunched beaksedge, is a member of the sedge family, Cyperaceae. It is a perennial herb, found throughout the eastern United States, from New York to Texas.

Rhynchospora cephalantha là loài thực vật có hoa trong họ Cói. Loài này được A.Gray miêu tả khoa học đầu tiên năm 1835.