Plants perennial. Culms 50-350 cm, decumbent, often rooting from the lower nodes; nodes glabrous; internodes glabrous, filled with spongy aerenchyma. Leaves evenly distributed; ligules membranous. Inflorescences narrow, condensed, cylindrical or spikelike panicles; branches appressed but not fused to the rachises, densely and evenly short ciliate on the ridges. Spikelets dorsally compressed, narrowly lanceolate, with 2 florets. Glumes unequal, membranous, with a definite rachilla internode between the 2 glumes; lower glumes no more than 1/2 as long as the spikelet, 1-3-veined; upper glumes subequal to or longer than the lower lemmas, membranous, not saccate, 3-7-veined; lower florets sterile; lower lemmas similar to the upper glumes; upper florets bisexual, much shorter than the upper glumes and lower lemmas; upper lemmas membranous to leathery, white at maturity, margins clasping the edges of the paleas basally but not distally, apices acute; paleas similar in texture to the lemmas; lodicules 2; anthers 3; styles 2, fused. Caryopses falling free from the lemmas and paleas. x = 10. Name from the Greek hymen, membrane, and achne, chaff, alluding to the membranous upper lemma, an unusual texture for the upper lemma in members of the Paniceae.
This project was made possible in part by the Institute of Museum and Library Services [MG-70-19-0057-19].