164 
spike 6 to 8 inches long; spikelets in pairs, very close, smooth, 
about 1% lines long, oblong, obtusish; occasionally with a long 
peduncled axillary spike, and sometimes the spikelets. with a 
third small sterile glume. 
9. PP. setaceum, Michx. (P. debile, Michx.)—Culms 1 to 1% 
feet high, very slender; spikes long exerted, about 3 inches long 
and slender; spikelets in two rows, about 34 inch long, very 
close ; fins narrow. 
10. P. ctiliatifolium, Muhl.—(P. dasyphyllum, E\\.)—Culms 
stouter, 114 to 2 feet high; leaves mostly longer and wider, 
smooth or hairy ; spikes thicker; spikelets generally larger, and 
in two or three rows. 
(c). Spikes 2 to 5, rarely more, not digitate. 
* Spikelets 1 line long or less. : 
11. P. cespitosum, Flugge.—Culms 1% to 2 feet high, 
simple, leafy below; spikes 2 to 4, about 1 inch distant, 1 to 14 
inches long, closely flowered; spikelets about half a line long, 
elliptical, minutely pubescent. 
Var. LONGIFOLIUM, leaves smooth much longer and narrower. 
12. P. Walterianum, Schultes.—Culms decumbent from a 
creeping rootstock, much branched; 1 to 2 feet long, smooth; 
leaves 3 to 4 inches long, acute, sheaths loose, the upper enclosing 
the lower spike; spikes 3 or more, approximate, with many 
from the lateral branches, 1 to 1% inches long; spikelets in two 
rows, ovate, I line long, smooth; rhachis broadly winged, the 
margins partly covering the spikelets. 
13. JP. lentiginosum, Presl.—Culms 2 to 3 feet high, often 
branching below, joints smooth; sheaths long and loose; leaves 
4 to 8 inches long, about % inch wide; panicle 3 to 5 inches long; 
spikes 3 to 5, alternate, 34 inch to 1% inches apart, the lower 
ones 3 to 4 inches long, upper shorter; rachis subflexuous, very 
narrow; spikelets about a line long, in pairs, broadly oval; sterile 
glumes slightly puberulent, minutely punctate and brown spotted ; 
generally with a minute third sterile glume as in Panicum, 
(350 Drummond, Texas.) 
* * Spikelets from 1 to 1% lines long. 
14. P. lividum, Trin.—Culms 2 feet or more high, branch- 
ing below, smooth; panicle about 4 inches long; spikes 4 to 5, 
