166 
Var. GLABRUM.—Culms decumbent and rooting at the base, 
spikelets smooth or nearly so. 
19. - P. racemulosum, Nutt.—Culms erect, 2 to 3 feet high, 
simple; leaves long, the lower ones with the sheaths white-hairy ; 
panicle erect, 4 to 6 inches long; spikes generally 3, lax, few- 
flowered, 3 to 4 inches long; rhachis narrow and flexuous, spike- 
lets in alternate pairs, distant, distinctly pedicelled, oblong-ovate, 
obtuse, about 1% lines long; sterile glumes smooth, seven-nerved. 
20. P. dilatatum, Poir., (P. ovatum, Trin.)—Culms 3 to 4 
feet high, simple, smooth; leaves lance-linear, acuminate, smooth; 
panicle 6 to 8 inches long, lax, cernuous; spikes 3 to 7, rarely 
more, 2 to 4 inches long, gradually shorter upwards, rather lax ; 
rhachis smooth and straight; spikelets in four rows, compressed, 
ovate, acute; sterile glumes about 1% lines long, acute, five- 
nerved, longer than the obtuse flowering ones, the lower one 
with scattered silky hairs, especially on the margins. 
Var. DECUMBENS; culms shorter and decumbent, the spikes 
usually 3 or 4. 
* * * Spikelets larger, 11% to 2 lines long. 
21. PLP. difforme, Le Conte.—Culms erect, 2 to 3 feet high, 
simple, leafy near the base; leaves 4 to 6 inches long, about 4 
lines wide, flat, upper surface and margins with scattered long 
hairs, which disappear with age, upper leaves very short; panicle 
short, of 2 or 3 rather dense spikes, 1% to 3 inches long; rhachis 
narrow aud flexuous; spikelets mostly single and in two rows, 
oval-oblong, obtuse, 1% to nearly 2 lines long; lower sterile 
glume slightly scabrous, five-nerved. Intermediate between 
P. leve and P. Floridanum. (3,570, A. H. Curtiss distribution.) 
22. P. Floridanum, Michx.—Culms_ erect, rigid, simple, 
tall; leaves long and narrow, hairy or smooth; spikes 2 to 6, 
thick, erect, 3 to 5 inches long; rhachis narrow and flexuous ; 
spikelets in two to four rows, about 2 lines long, smooth, obtuse, 
ovate, three to five-nerved, finely reticulate-striate. 
Var. TYPICA; leaves and sheaths rough hairy, spikes 2 to 3. 
Var. glabrata, Englm.; leaves smooth, wider, spikes more _ 
numerous, usually 5 to 7. 
23. JP. giganieum, Baldw. (ined.)—Culms simple, erect, 3 to 
5 feet high; leaves long and wide, the lower 18 inches long, and 
