HABIT Perennial. Rhizomes short; pachymorph. Culms erect; 300-460 cm long; woody. Culm-internodes terete. Lateral branches dendroid. Branch complement many; flabellate; with subequal branches; thinner than stem. Culm-sheaths deciduous; auriculate. Culm-sheath blade ovate; constricted at base. Ligule an eciliate membrane. Leaf-blade base with a brief petiole-like connection to sheath. Leaf-blades lanceolate. INFLORESCENCE Inflorescence a panicle, or comprising only a few spikelets; axillary. Panicle open. Spikelets solitary. Fertile spikelets pedicelled. Pedicels filiform. FERTILE SPIKELETS Spikelets comprising 7-10 fertile florets; with diminished florets at the apex. Spikelets linear; laterally compressed; 60-75 mm long; breaking up at maturity; disarticulating below each fertile floret. Rhachilla internodes pilose. GLUMES Glumes persistent; shorter than spikelet; firmer than fertile lemma. Lower glume ovate; 0.7-0.75 length of upper glume; coriaceous; without keels; 5 -veined. Lower glume apex acute. Upper glume ovate; 0.6-0.7 length of adjacent fertile lemma; coriaceous; without keels; 11 -veined. Upper glume apex acute. FLORETS Fertile lemma ovate; chartaceous; without keel; 13 -veined. Lemma apex acute. Palea 1.1 length of lemma; chartaceous; 18 -veined. Palea keels winged; ciliolate. Apical sterile florets resembling fertile though underdeveloped. FLOWER Lodicules 3; glabrous, or ciliate. Anthers 3. Stigmas 2. Ovary umbonate; pubescent on apex. FRUIT Caryopsis with free brittle pericarp; ellipsoid. Embryo 0.15 length of caryopsis. Hilum linear; 1 length of caryopsis. DISTRIBUTION South America.