Rhynchospora cephalantha A.Gray

Erect perennial to 1 m, with clustered stems; lvs 1.5–4.5 mm wide; glomerules 1–7, globose or subglobose (the lower spikelets ± reflexed), the terminal one 8–20 mm thick, the lateral subsessile or on peduncles to 2 cm; spikelets dark brown, 3–5.5 mm, the solitary fl terminal and perfect; bristles 6, about equaling the tubercle, usually retrorsely barbellate; achenes obovate-pyriform, 1.3–2.5 mm, two-thirds as wide, smooth, dark brown and somewhat concave near the raised margin, elevated toward the center into a prominent pale umbo; tubercle flattened, triangular-subulate, two-thirds to fully as long as the achene. Wet acid soil on the coastal plain; N.J. to Fla., La., and Cuba. Many authors maintain that R. microcephala Britton, with small, round-topped achenes 1.3–1.6 mm, small spikelets 3–4 mm, and smaller glomerules, not over 1 cm wide, should be distinguished from R. cephalantha proper, with larger, often truncate achenes 1.8–2.5 mm, larger spikelets 4–5.5 mm, and larger glomerules, some 1.5–2 cm wide.