Plants perennial; cespitose, shortly rhizomatous, reedlike. Culms 1.5-4 m, woody, persistent, glabrous, usually not branched above the base; internodes solid. Leaves cauline, distichous; sheaths open; auricles sometimes present; ligules membranous to somewhat leathery, entire, minutely erose, or ciliolate; pseudopetioles poorly developed; blades flat, disarticulating from the sheaths when old, cross venation not evident. Inflorescences terminal, open diffuse panicles; disarticulation at the pedicel bases, subsequently below the spikelets. Spikelets solitary, pedicellate, terete, with 2(3-4) florets, lowest floret in each spikelet sterile; rachilla extension prolonged, often terminating in a rudimentary floret. Glumes membranous, shorter than the florets, 0-1-veined, obtuse; lowest florets equaling the upper florets, sterile; lowest lemmas membranous, 1-3-veined; lowest paleas not present; upper florets bisexual; upper lemmas membranous, 3-veined, unawned, marginal veins with papillose-based hairs, hairs 0.8-1.5 mm, strongly diverging at maturity; upper paleas about 1/2 as long as the lemmas, apices notched; lodicules 2, free, broadly cuneate, truncate to irregularly lobed; anthers 2(3). Caryopses nearly spherical to broadly ovoid; embryos about 3/4 as long as the caryopses; hila subbasal, punctate. x = 12. Name from the Greek thysanos, fringe, and laina, cloak, a reference to the second lemma.