impolitus (L.) = rough, unpolished. Referring to the tuberculate culms.
WCM Protologue Reference:
Kunth, Enum. Pl. 3: 404 (1841)
Vegetative parts: plants tufted or tangled, 0.3-0.6 m tall, basal diameter 0.01-0.05 m, crown diameter 0.1-1.5 m, compact, without spreading rhizomes or stolons or with stolons (short, but leading to plants with a diffuse base). Fertile culms branching, roughly warty, olivaceous, 0.3-0.6 m tall, diameter at base 0.7-1.8 mm, diameter at apex 0.3-0.8 mm. Sheaths closely convoluted, 8-25 mm long, reddish-brown, surface usually roughly tubercled, apical margins coriaceous, like the rest of the body or narrowly membranous, hyaline shoulders tall, acute, hyaline shoulder 0.2-1 of sheath body length, apex, excluding the membranous lobes, obtuse or truncate. Sheath-mucro penicellate, straight and erect, 2-6 mm long, large membranous shoulders are soon lost. Males: male inflorescence with 2-5 spikelets or 6-10 spikelets or 11-20 spikelets, paniculate (are remarkably distichous), 25-80 mm long, 10-30 mm wide. Male inflorescence spathes persistent, like the floral bracts, coriaceous or chartaceous. Male flowers in spikelets. Male spikelets erect on stiff pedicels or sessile, oblong or ovate, apex rounded, 8-14 mm, 6-10 mm, with 4-6 flowers, pedicels absent ie spikelets sessile or shorter than the spikelets, terete or angular. Male bracts taller than flowers, 5.5-7 mm long, oblong, acute, chartaceous or cartilaginous, bract upper margin like body of bract, bract awn minute or absent, margins broadly hyaline, centre portion more darkly pigmented. Male flower 4-4.5 mm long. Male tepals sepals and petals the same rigidity or sepals more rigid than petals, chartaceous, petals membranous, oblong, inner and outer tepals the same length. Male outer lateral tepals conduplicate, glabrous or keel sparsely villous. Anthers 2-2.5 mm long, included in the flowers. Pistillode present (minute). Females: female inflorescence paniculate (Remarkably distichous), 40-120 mm long, 20-45 mm wide, with 6-10 spikelets or 11-20 spikelets. Female spathes like floral bracts or shorter than the spikelets, persistent, coriaceous. Female spikelet sessile or pedicel simple, obovate or obtriangular, apex truncate or rounded, 11-15 mm long, with 3-5 flowers, with 0-1 sterile bracts. Female bracts taller than flowers, 7-10 mm long, oblong, acute, coriaceous or cartilaginous, apical margin membranous (upper half), darker than body of bract, awn minute or absent. Female flower 4.5-6 mm long, without a fleshy pedicel. Female tepals cartilaginous, glabrous and smooth, at least as tall as nut, wrapped around it and obscuring the surface, midrib flush with the tepal body, apices rounded or acute or acuminate, inner whorl shorter than outer. Female outer lateral tepals keeled or winged, wings entire or deeply lobed, wider than body, hidden by bracts, or bracts are shorter than flowers or exserted past bracts, 5-6 mm long. Female odd outer tepal oblong, 3.5-5.5 mm long. Female inner tepals oblong, 4-4.5 mm long. Staminodes absent. Styles feathery, white, 3. Style bases seated on a stylopodium. Ovary with 1 locule, indehiscent. Fruit: indehiscent fruits with a softer ovary wall. Perianth presence on fruits persistent, winged. Shape of winged dispersal unit orbicular. Nut apex smooth, without a distinct cap, wall smooth, 2.4-3 mm long, (0.72-)0.76(-0.84) mm diam., shape in side view elliptical or oblong, shape in top view round in cross section, brown or tan. Elaiosome absent.