12. Muhlenbergia Cuspidata (Torr.) Nash. Prairie Rush-Grass

Fig. 450

Vilfa cuspidata Torr.; Hook. Fl. Bor. Am. 2: 238. 1840. Sporobolus cuspidatus Wood, Bot. & Fl. 385. 1870.

Sporobolus brevifolius Scribn. Mem. Torr. Club, 5: 39. In part. 1894.

Smooth and glabrous, culms 1°-2° tall, erect, simple above, branched at the base. Sheaths shorter than the internodes; ligule a mere ring, 1/4" long or less, erose-trun-cate; blades 1-4' long, less than 1" wide at the base, erect, involute-setaceous, at least when dry; panicle 1 1/2'-5' in length, slender, its branches 1/4'-1' long, appressed; spike-lets 1 1/4'-1 1/2' long, the outer scales half to three-quarters as long, acuminate or cuspidate, scabrous on the keel; third scale long-acuminate and cuspidate, sparingly scabrous.

In dry soil, Manitoba to Alberta, south to Missouri and Kansas. Aug.-Sept.

12 Muhlenbergia Cuspidata Torr Nash Prairie Rush G 450

13. Muhlenbergia Gracillima Torr. Filiform Dropseed

Fig. 451

M. gracillima Torr. Pac. R. R. Rept. 4: 155. 1875.

Glabrous, culms 4'-14' tall, from a slender creeping rootstock, erect, slender, simple, rigid. Sheaths smooth; ligule 1"-2" long, entire and acuminate, or variously cleft, with acuminate teeth; blades l'-2' long, involute-setaceous, smooth or somewhat scabrous, rigid, the basal numerous, usually strongly recurved, the 1-3 culm blades erect or ascending; panicle 2'-9' in length, open, the branches finally widely spreading, 1'-3' long, filiform; spikelets about as long as the filiform pedicels which are clavate-thickencd at the apex; outer scales unequal, usually awn-pointed or short-awned, slightly scabrous; third scale 1 1/4"- 1 1/2" long, longer than the outer ones, sometimes twice as long, scabrous; awn I"-2" long.

On prairies, Kansas to Colorado, south to Texas and Arizona. Sept.-Oct.

13 Muhlenbergia Gracillima Torr Filiform Dropseed 451

14. Muhlenbergia Pungens Thurb. Prairie Dropseed

Fig. 452

Muhlenbergia pungens Thurb. Proc. Acad. Phila. 1863: 78. 1863.

Culms 6'-15' tall from a creeping rootstock, erect from a decumbent branching base, rigid, minutely pubescent. Sheaths overlapping, cro\\ded at the base of the culm, scabrous; ligule a ring of soft silky hairs; blades 1'-2' long, involute-setaceous, rigid, scabrous; panicle 3'-6' in length, open, the branches 2'-2 1/2' long, single, distant, much divided from near the base, the divisions apparently fascicled; spikelets on long pedicels, which are clavate-thickened at the apex; outer scales, when mature, equalling or often shorter than the body of the third one, scabrous, especially on the keel; third scale, when mature, \"-\" long, scabrous, the awn shorter than its body.

On prairies, Nebraska to Utah, south to Texas and Arizona. Blow-out-grass. Aug.-Sept.

14 Muhlenbergia Pungens Thurb Prairie Dropseed 452

15. Muhlenbergia Capillaris (Lam.) Trin. Long-Awned Hair-Grass

Fig. 453

Stipa capillaris Lam. Tabl. Encycl. 1: 158. 1791. Muhlenbergia capillaris Trin. Unifl. 191. 1824.

Glabrous, culms 1 1/2°-4° tall, erect, simple, smooth or nearly so. Sheaths smooth, the lower short and overlapping, the upper ones much longer; ligule about 2" in length; blades 6'-1° long, 1"-2" wide, scabrous; panicle 7'-1° in length or more, diffuse, the capillary branches 4'-8' long, at length widely spreading; spike-lets on long hair-like pedicels which are clavate-thickened at the apex; outer scales unequal, acute or short-awned, slightly scabrous; third scale, exclusive of the awn, 2" long, about twice as long as the first one, scabrous, the awn 3"-9" in length.

In dry sandy or rocky soil, Massachusetts to Kansas, Florida and Texas. Bahamas and Cuba. Panicle usually light purple. Sept.-Oct.

15 Muhlenbergia Capillaris Lam Trin Long Awned Hai 453

Muhlenbergia glabriflorus Scribn., an imperfectly known species, is reported from Illinois. It is said to resemble M. mexicana, and to differ from that species in the glabrous softer scales.