a 
GRASS FAMILY. I5!I 
Panicle open, the branches more or less spreading, at least at maturity. 
Pedicels equalling or shorter than the spikelets; first scale about half as long as the second. 
Branches of the panicle verticillate. 
Spikelets 4"" long, green. 10. S. argulus, 
Spikelets 1(’'-1'2"' long, purple. Ir. S. Junceus. 
Branches of the panicle alternate or sometimes sub-verticillate. 
Spikelets about 1'’ long; first scale lanceolate. 
Sheaths naked or sparingly ciliate at the throat; panicle usually exserted. 
12. S. atrotdes. 
Sheaths densely pilose at the throat; base of the panicle generally included. 
13. S. cryplandrus, 
Spikelets 2'’-23;"' long; first scale subulate. 14. S. helerolepts. 
Pedicels at least twice the length of the spikelets; first scale about equalling the second. 
Culms erect, simple; leaves elongated. 
Culms slender, from an annual root; outer scales about half the length of the spikelet. 
15. S. serotinus. 
Culms stout, from a horizontal rootstock: outer scales slightly shorter than the spikelet. 
16. S. compressus. 
Culms decumbent and branched below; leaves short. 17. S. aspertfolius. 
1. Sporobolus Asper (Michx.) Kunth. Rough Rush-grass. (Fig. 341.) 
Agrostis aspera Michx. Fl. Bor. Am. I: 52. 1803. 
Sporobolus asper Kunth, Enum. 1: 210, 1833. 
Sporobolus asper var. Drummondii Vasey, Contr. 
U. S. Nat. Herb. 3: 60. 1892. 
Culms 2°-5° tall, erect, simple, smooth and 
glabrous. Sheaths shorter than the internodes; 
ligule a mere ring, less than 4’ long, naked; 
leaves 3/-15’ long, 1//-2/’ wide at the base, 
attenuate into a long slender involute tip, 
smooth and glabrous beneath, scabrous above, 
or somewhat hairy at the base; panicle 2/-5/ in 
length, linear, strict, its branches 1/-2’ long, ap- 
pressed; spikelets 3/’-4’’ long, the outer scales 
unequal, acute; third scale pubescent at the base, 
much longer than the second and greatly ex- 
ceeded by the long-acuminate almost awned 
palet. 
In dry soil, Delaware to Illinois, south to Florida 
and Texas. Aug—Sept. 
2. Sporobolus longifolius (Torr.) Wood. Long-leaved Rush-grass. 
(Fig. 342.) 
Agrostis longifolia Torr. Fl. U. S. 1: 90. 1824. 
Sporobolus asper Vasey, Contr. U. S. Nat. Herb. 3: 
59. 1892. Not Kunth, 1833. 
a eecarecs longtfolius Wood, Class-book, 775. 
1861. 
Culms 114°-3%° tall, erect, simple or occa- 
sionally branched, smooth and _ glabrous. 
Sheaths shorter than the internodes; ligule very 
short, minutely ciliate; leaves 4’-18’ long, 1/’— 
2// wide at the base, attenuate into a long slen- 
der involute tip, smooth and glabrous beneath, 
scabrous and hairy at the base above; panicle 
more or less included in the upper sheath, 3/— 
to’ in length, linear, strict, the branches 1/-2 
long, erect; spikelets 2’/-2'4’’ long; outer scales 
unequal, acutish, glabrous, the lower shorter; 
third scale glabrous, acutish or obtuse, exceed- 
ing the second and equalling or a little shorter 
than the obtuse palet. 
In dry soil, Maine to Pennsylvania, Missouri and 
Kansas, south to Florida and Texas. Aug —Sept. 
