12. Sporobolus Argutus (Nees) Kunth. Pointed Dropseed-Grass

Fig. 475

Vilfa arguta Nees, Agrost. Bras. 2: 395. 1829. Sporobolus argutus Kunth, Enum. 1: 215. 1833.

Culms 1° tall or less, erect, or somewhat decumbent at the base, simple or sometimes branched, smooth and glabrous. Sheaths shorter than the internodes, their margins sometimes hirsute at the top; ligule a ring of short hairs; blades 1'-2' long, 1"-2" wide at the base, acuminate, smooth and glabrous beneath, scabrous and often sparingly hairy at the base above; panicle 1 1/2'-3' in length, the branches 1/2'-1' long, verticillate, at first appressed, finally widely spreading; spikelets 3/4" long; outer scales smooth and glabrous, the first rounded or obtuse, one-quarter the length of the acute second one; third scale about equalling the second, acute.

In sandy and rocky places, Kansas and Colorado, south to Texas and Mexico. Also in the West Indies. July-Sept.

13. Sporobolus Gracilis (Trin.) Merrill. Purple Dropseed-Grass. Wire-Grass

Fig. 476

Agrostis juncea Michx. Fl. Bor. Am. 1: 52. 1803. Not

Lam. 1783. Vilfa gracilis Trin. Mem. Acad. St. Petersb. VI. 52: 74.

1840. Sporobolus junceus Kunth, Rev. Gram. 1: 68. 1829. S. ejuncidus Nash, in Britt. Man. 106. 1901. S.. gracilis Merrill, Rhodora, 4: 48. 1902.

Glabrous and smooth throughout, culms 1°-2° tall, tufted, erect, slender, simple. Sheaths shorter than the internodes; ligule very short; blades filiform or setaceous, the basal 6'-1° long, numerous, those of the culm few, I'-3' long; panicle 3'-7' length, open, the branches verticillate, the lower 1'-2' long, widely spreading; spikelets 1 1/4"-1 1/2", purple, the outer scales very unequal, the first obtuse or acutish, one-fourth to one-third the length of the acute second one; third scale subacute or blunt, equalling the second and the obtuse palet.

Dry sandy soil, Virginia to Florida, west to Texas. Rush-grass. Aug.-Sept.

14. Sporobolus Airoides Torr. Hair-Grass Dropseed

Fig. 477

Agrostis airoides Torr. Ann. Lye. N. Y. 1: 151. 1824. S. airoides Torr. Pac. R. R. Rept. 7: Part 3, ax. 1856.

Culms 1 1/2°-3° tall, erect, simple, smooth and glabrous. Sheaths generally shorter than the internodes, sometimes sparsely ciliate at the throat; ligule very short; blades smooth beneath, scabrous above and sometimes sparingly hairy near the base, 1/2"-1 1/2" wide at the base, attenuate into a long slender involute point, the basal about one-half as long as the culm, the upper culm leaves 2'-5' in length; panicle 5' - 15' long, usually ex-serted, the branches alternate or the upper verticillate, at length widely spreading, the lower 3'-7' long; spike-lets 3/4"-1" long, the scales acute, glabrous, the outer unequal, the lower one about half as long as the upper; third scale equalling the second and the palet.

Prairies, Nebraska to Montana, California and Texas. Rush-grass. Salt-grass. Fine-top salt-grass. Aug.-Sept.