Perennial grasses, with usually flat leaf-blades, and a narrow contracted spike-like panicle. Spikelets numerous. Scales several, the outer 2 empty ones 1-nerved, the flowering scales broad, rounded at the apex, 3-nerved, the nerves glabrous, the lateral ones vanishing below the margin, the midnerve at the margin or sometimes excurrent as a short tip, the callus pilose; palet 2-keeled. Stamens 3. Styles short, distinct. Stigmas plumose. Grain free, enclosed in the scale. [Greek, in reference to the round flowering scales.]

Species 4 or 5, natives of warm countries. Type species: Rhombolytrum rhomboideum Link.

1. Rhombolytrum Albescens (Vasey) Nash. White Prairie-Grass

Fig. 571

Triodia albescens Vasey, Bull. U. S. Dept. Agric. Div.

Bot. 12: Part 2, 33. 1891. Sieglingia albescens Kuntze; L. H. Dewey, Contr. U. S.

Nat. Herb. 2: 538. 1894. R. albescens Nash, in Britt. Man. 129. 1901.

Culms tufted, erect, smooth and glabrous, 12'-20' tall, the sterile shoots one-half as long as the culm or more. Sheaths shorter than the internodes, smooth; ligule a ring of short hairs; blades smooth beneath, roughish above, acuminate, 2 1/2'-11' long, 1"-2" wide; panicle dense and contracted, white, 2 1/2'-5' long, 1/4'-3/4' broad, its branches erect or ascending, 1' or less long; spikelets about 7-11-flowered, 2"-2 1/2" long, the empty scales white, 1-nerved, about equal; flowering scales about 1 1/2" long, 3-nerved, the lateral nerves vanishing below the apex, all the nerves glabrous, the midnerve excurrent in a short scabrous point, denticulate and irregularly and obscurely lobed at the truncate apex.

Prairies, Kansas to New Mexico and Texas. Aug.-Sept.