499 
first empty glume one. third shorter than the floret.—Low land, southern Texas to 
Florida. . 
4. P. vaginatum Sw. Culms ascending from a long creeping base, 1 to 4, 
dm. high: leaves distichous, divergent, usually involute, almost subulate pointed ; 
sheaths equaling or exceeding the internodes: spikes a pair (rarely 3), 3 to 5 cm. 
long on clavate peduncles: spikelets acute, smooth, about 4 mm, long.—Swamps 
and wet places near the coast, eastern Texas to Florida. 
5. P. distichum L. (Jornr Grass.) Culms ascending, 3 to 6 dm. high, from a 
creeping base: leaves linear-lanceolate, 1 to 1.5 dm. long: spikes 1 terminal and 
1 (rarely 2) about 1 em. below, 2 to 6 em. long: spikelets crowded, subacute, 
pubescent or nearly smooth, nearly 3 mm. long.—Moist places throughout Texas and 
across the continent, 
6. P. setaceum Michx. Culms decumbent or erect, 5 to 7 dm. high: leaves lan- 
ceolate, mostly flat, 1 to 2dm. long: spikes 5 to 10 em. long, one terminal and usu- 
ally one or more sessile 2 to 3 cm. below; rachis narrow: spikelets rotund, 1 to 2 
inm. in diameter.—Hillsides, Var. CILIATIFOLIUM Vasey hasstouter and taller culms, 
and leaves 6 to 10 mm. wide and hairy on the-margins or all over.—With the type, 
in open woods throughout eastern and northern Texas. 
+ + Spikes 3 to 10, or sometimes reduced to 2 in No. 7. 
++ Spikelets rotund, less than 3 mm, long. 
7. P. Drummondi Vasey. Culms 5to10 dm. high, often branching below: leaves 
lanceolate, about 1 dm. long and 1 cm. wide: spikes 2 to 4, arcuate, spreading, 5 to 
10 em. long; rachis narrow: spikelets in 2 or 3 indistinct rows, 2 mm. in diameter, 
pubescent, brownish dotted, generally with a small extra outer glume.— Woods 
and shady ravines, eastern Texas to Florida. 
8. P. leeve Michx. Culms usually erect, 5 to15 dm. high, rarely branching: spikes 
3 to 6, somewhat spreading, 5 to 10 em. long, 3 em, or more apart, hairy in the axils; 
rachis about 1 mm. wide: spikelets in two rows, smooth, nearly 3 mm. long.—Moist 
soil, central Texas to the Atlantic States. Var. BREVIFOLIUM Vasey has rather slender 
culms 4 to 8 din. high, leaves 1 to 1.5 dm. long and 1 em. wide, and spikelets slightly 
smaller than in the species. Var. ANGUSTIFOLIUM Vasey has culms usually 1m, high 
or more, long and narrow leayes, and spikelets slightly larger than the species. 
9, P. precox Walt. Culms about 1m. high, simple: leaves 2 to 4 dm, long, less 
than 1 cm. wide: spikes 3 to 6, somewhat spreading, 3 to 5 cm. long; rachis 1 mm. 
wide: spikelets mostly in 3 rows, smooth, 2 mm. in diameter.—In moist soil, extend- 
ing from the south Atlantic States to Texas. 
++ ++ Spikelets lanceolate or oblong, less than 3 mm, long. 
10. P.lividum. Trin. Culms 5 to 8 dm. high, compressed below, sometimes 
branching near the base: leaves narrowly lanceolate, slender-pointed, about 2 dm. 
long: spikes 4 to 6, arcuate, nearly erect, 3 to 4 em, long ina rather close te:minal 
panicle; rachis 2 mm. broad: spikelets oval or broadly oblanceolate, 2 mm. long, 
smooth.—Near the coast or in wet places in the river valleys. 
11. P. Buckleyanum Vasey. Culms ascending, 5 to 10 dm. high, often branch- 
ing below: leaves narrow, flat or conduplicate: spikes 2 to 6, nearly straight, 
spreading, 4 to 8 cm, long, in a loose panicle; rachis 2 mm. wide: spikelets broadly 
lanceolate, subacute, nearly 3 mm. long; pubescent empty glumes longer than the 
obtuse floret.—Moist places, southern Texas. 
12. P. pubiflorum Rupr. Culms 5 to 10 dm. high, erect or ascending from a 
creeping base, pubescent at the nodes: leaves flat, lanceolate, 1 to 2 dm. long, about 
lem. wide: spikes 3 to 6, spreading, 4 to 8 cm. long; rachis 2 mm. wide: spikelets 
in 2 to 4 rows, oblong, obtuse, nearly 3 mm. long, pubescent.—In moist soil, eastern 
Texas. Var. GLAUCUM Scribn. has rigid culm and leaves and is glaucous throughout,— 
Southwestern Texas and northern Mexico. 
