HABIT Perennial. Culms erect; 40-350 cm long. Ligule absent. INFLORESCENCE Monoecious; with male and female spikelets in the same inflorescence. Synflorescence on a separate leafless culm. Inflorescence a panicle. Panicle spiciform. Sexes segregated; with male below. Spikelets solitary. Fertile spikelets pedicelled. Male spikelets pedicelled. Pedicels oblong. FERTILE SPIKELETS Spikelets comprising 1 basal sterile florets; 1 fertile florets; with diminished florets at the apex. Spikelets lanceolate; dorsally compressed; 9-17 mm long; falling entire. GLUMES Glumes shorter than spikelet. Lower glume lanceolate; 1-1.3 length of upper glume; herbaceous; 2-keeled; 3-7 -veined. Lower glume surface flat. Lower glume apex truncate, or obtuse. Upper glume lanceolate; 0.33 length of adjacent fertile lemma; herbaceous; without keels; 3-6 -veined. Upper glume apex truncate, or obtuse. FLORETS Basal sterile florets barren; without significant palea. Lemma of lower sterile floret lanceolate; herbaceous; 5-9 -veined; ribbed; obtuse. Fertile florets female. Fertile lemma lanceolate; herbaceous; without keel; 5-13 -veined. Lemma lateral veins ribbed. Lemma apex truncate, or obtuse. Palea tightly convolute around flower; 1.3-1.5 length of lemma; spongy; 5-11 -veined. Palea keels approximate. Apical sterile florets 1 in number; barren; linear. FLOWER Lodicules absent. Anthers 2. Stigmas 2. FRUIT Caryopsis with adherent pericarp; fusiform. Embryo 0.2 length of caryopsis. Hilum linear; 0.7 length of caryopsis. MALE Male spikelets similar to female but less developed; lanceolate. Male spikelet glumes 2. DISTRIBUTION South America.