5. Fimbristylis vahlii (Lam.) Link
Pl. 76 e–g; Map 290
Plants annual, tufted,
lacking rhizomes. Stems few to many, 1.5–10.0 cm long, ascending to
spreading, glabrous or less commonly minutely hairy. Leaves with blades
1–15 cm long, glabrous or minutely hairy along the veins and the usually
somewhat curled margins, the top of the sheath without a ligule. Inflorescences
small headlike clusters of sessile 3–8 spikelets, the 2–4 bracts
mostly much longer than and partially hiding the inflorescence. Spikelets
4–9 mm long, lanceolate to ovate or less commonly oblong in outline,
usually pointed at the tip, the scales 1.1–1.4 mm long, lanceolate to
ovate, the tip pointed, the midvein usually extended past the scale tip as a
short point, pale green or translucent white to light tan, glabrous. Stamen 1.
Stigmas 2, the style usually with minute papillae below the branches. Fruits
0.5–0.7 mm long, obovate in outline, slightly flattened (broadly oval in
cross-section), the surface reticulate, ribbed with 10–15 vertical rows
of cells, light yellow to nearly white, sometimes somewhat iridescent. 2n=20.
Scattered in southern Missouri (southern U.S. south to South America). Mudflats along rivers, sandy margins of
ponds, sloughs, and canals, and moist, sandy, disturbed areas.
This species usually
forms dense tufts of fine, spreading, hairlike stems, with the spikelets
frequently partially obscured by the long inflorescence bracts and leaves.