Perennial tufted grasses, with flat leaf-blades, and diffuse panicles, which break away when mature and act as tumble-weeds. Spikelets 1-flowered, solitary, or rarely in pairs. Scales 4, or sometimes 3 by the abortion of the first minute scale; second scale 3-nerved; third scale 5-7-nerved; fourth scale elliptic, acute, indurated in fruit, the delicate and hyaline margins flat, not inrolled, enclosing a palet of similar texture and a perfect flower. Grain free, enclosed in the scale and palet. [Greek, from the delicate hyaline margins of the fruiting scale.]

Species 4 or 5; besides the following typical one 3 or 4 others occur in Australia.

1. Leptoloma Cognatum (Schultes) Chase. Diffuse Crab-Grass

Fig. 284

Panicum nudum Walt. Fl. Car. 73. 1788?

Panicum divergens Muhl. Gram. 120. 1817. Not H.B.K. 1815. Panicum cognatum Schultes. Mant. 2: 235. 1824. Panicum autumnale Bosc; Spreng. Syst. 1: 320. 1825. Leptoloma cognatum Chase, Proc. Biol. Soc. Wash. 19:

192. 1906.

Culms erect or decumbent, 1°-2° tall, generally much branched at the base, slender. Sheaths shorter than the internodes, the upper glabrous, the lower sometimes densely pubescent; leaves 1 1/2'-4' long, 1"-3" wide, ascending, acuminate, glabrous; panicle 5'-12' long, bearded in the axils, the lower branches 4'-8' long, at first erect with the lower portion included in the upper sheath, finally exserted and widely spreading at maturity; spikelets lanceolate, about 1 1/2" long, acuminate, glabrous or pubescent, on capillary pedicels of many times their length; first scale minute; second and third equal, acute, glabrous or sometimes villous, the fourth lanceolate, 1 1/4" long.

In dry soil, Illinois to Florida, Minnesota, Kansas and Arizona. Recorded from New Hampshire. July-Sept.

1 Leptoloma Cognatum Schultes Chase Diffuse Crab G 284