Perennial tufted grasses with stiff culms and a panicle composed of scattered distant widely spreading rigid branches. Spikelets scattered and distinct, singly disposed in two rows, sessile, 4-6-flowered. Scales 6-8, firm; two lower scales empty, acuminate, about equal, the first 1-nerved, the second usually 3-nerved; flowering scales very acute, becoming harder in fruit, 3-nerved, the nerves glabrous, the lateral nerves vanishing at the margin below the apex; palet compressed, its two nerves ciliolate, gibbous at the base, obtuse at the apex. Stamens 3. Styles distinct. Stigmas plumose. [Greek, in reference to its rigid branches.]

A monotypic genus of south central United States.

1. Acamptoclados Sessilispicus (Buckley) Nash. Stiff Prairie-Grass

Fig. 556

Eragrostis sessilispica Buckley, Proc. Acad. Phila. 1862: 97.

1862. Diplachne rigida Vasey, Grasses S. W., Part 2. pl. 41. 1891. A. sessilispicus Nash, in Small, Fl. SE. U. S. 140. 1903.

Culms 8'-3 1/2° tall, erect, simple, smooth and glabrous. Sheaths short, crowded at the base of the culm, smooth, pilose at the summit; ligule a ring of short hairs; blades 2'-6' long, 3/4"- 1 1/2" wide, rough above, glabrous or sparingly pilose beneath; panicle 8'-16' in length, the branches stout, rigid, widely diverging; spikelets scattered, closely sessile, appressed, 5-12-flowered, 4"-7" long, empty scales about equal in length, acute; flowering scales very acute, about 2" long, the lateral nerves very prominent.

Prairies, Kansas to Texas. Aug.-Sept.

1 Acamptoclados Sessilispicus Buckley Nash Stiff P 556