Grasses with narrow, flat or involute leaf-blades and contracted or open panicles. Spike-lets shortly pedicelled, 2-6-flowered, the glabrous rachilla articulated between the flowers, the internodes very long. Scales 4-8, membranous, the lower 2 empty, keeled, the flowering scales dorsally rounded at the base, 3-nerved, the lateral nerves pilose, deeply 2-lobed at the apex, long-awned between the lobes, the callus long and subulate, pubescent on the outer surface; palet 2-keeled, the keels long-ciliate. Stamens 3. Styles short, distinct. Stigmas plumose. Grain free, enclosed in the scale. [Greek, referring to the 3 divisions of the flowering scales.]

Species 3, natives of the eastern and southern parts of North America. Type species: Triplasis americana Beauv.

1. Triplasis Purpurea (Walt.) Chapm. Sand-Grass

Fig. 565

Aira purpurea Walt. Fl. Car. 78. 1788. Tricuspis purpurea A. Gray, Man. 589. 1848. Triplasis purpurea Chapm. Fl. S. U. S. 560. 1860. Sieglingia purpurea Kuntze, Rev. Gen. PI. 789. 1891.

Culms 1°-3° tall, erect, prostrate or decumbent, smooth and glabrous or the nodes pubescent. Sheaths shorter than the internodes, rough; ligule a ring of short hairs; blades 1/2'-2 1/2' long, 1" wide or less, rigid, scabrous, sometimes sparsely ciliate; panicle l' - 3' in length, the branches rigid, finally widely spreading, the lower 3/4'-1 1/2' long; spikelets 2-5-flowered, 2 1/2"-4" long, the joints of the rachilla half as long as the flowering scale; lower scales glabrous; flowering scales oblong, 2-lobed at the apex, the lobes erose-truncate, the nerves strongly ciliate, the middle one excurrent as a short point; palets long-ciliate on the upper part of the keel.

In sand, especially on sea beaches, Maine to Texas, and along the Great Lakes. Also from Illinois and Nebraska to Texas. Plant acid. Aug.-Sept.