Pentapogon lacustris

Detailed description

Tufted, reddish-green grass up to 300 mm tall. Culms erect over topped by dense, cylindric panicles, these much exceeding laves at maturity. Branching extravaginal. Leaf-sheath chartaceous, glabrous, light green to light reddish brown, ribs more prominent above. Ligule 2.3 mm, erose, tapering centrally to a fine tip, undersides smooth, upper surface slightly ribbed, sparsely scabrid on ribs; margins finely scabrid, apex cucullate. Culm 100–240 mm, erect or geniculate ta base, nodes hidden by leaf-sheaths, internodes glabrous. Panicle 15–45 × 5–8 mm, cylindric, compact, dense, glossy amber to purple-green; rachis smooth, branches and pedicels sparsely finely scabrid. Spikelets 5–7 mm, purplish green. Glumes subequal, 1-nerved, submembranous, elliptic-lanceolate, acute, smooth, keel finely scabrid on upper ⅔. Lemma 4–5 mm, ⅔–⅘ length of glumes, subcoriaceous, smooth below, finely papillose to prickle-toothed above, more or less elliptic, apex shortly bifid; awn 3.5–4.5 mm, from upper ¼ of lemma, twisted about twice at base, more or less recurved above. Palea c. ⅔ length of lemma, hyaline, keels thickened, faintly prickle-toothed above. Callus hairs 0.3–1.0 mm. Rachilla prolongation 0.5–1.0 mm, bearing minute hairs throughout except at glabrous apex. Lodicules 0.4–0.5 mm long. Anthers 0.30–0.65 mm. Ovary 0.6 mm; stigma-styles 1.0–1.5 mm long. Seed 2.0 × 0.6 mm, with dehisced anthers entangled in stigma remnants.