24 



spike-like, 6 to 8 inches long, of numerous appressed slender, single, or 

 fascicled branches, the lower ones remote; spikelets ovate-lanceolate, 

 acutish, about 1 line long, lower glume acute, keeled, half as long as 

 the spikelet, the second a little shorter than the third, which equals the 

 acutish perfect flower ; second and third glumes strongly three to five 

 nerved, sterile flower triandrous. Closely resembles the preceding. 

 Ponds and swamps, Florida to Texas. 



9. P. obtusum, E. B. K. — Culms 1£ to 2 feet high, firm, leafy; send- 

 ing off long (sometimes 8 to 10 feet) runners from the base; leaves 4 to 

 6 inches long, 2 to 3 lines wide; pauicle 3 or 4 inches long, nar- 

 row, composed of four to seven approximate, appressed, sessile branches, 

 the lower ones about 1 inch long, the upper becoming very short, 

 densely flowered ; spikelets mostly in alternate pairs of which one is 

 sessile, the other short-pedicelled, forming three to four rows, turgid, 

 oblong, obtuse, and 1^- lines long, lower glume two-thirds as long as the 

 spikelet, five-nerved, second glume seven-nerved, third five-nerved, a 

 little longer than the fertile flower; sterile flower triandrous. 



Mexico, Texas, New Mexico to Colorado. 



10. P. reticulatum, Torr.— Culms 10 to 15 inches high, much branched 

 below, leafy; leaves 1J to 3 inches long, acute, scabrous or pubescent, 

 as also are the sheaths; panicle 2 to 3 inches long, lateral ones shorter, 

 close or dense; branches single or fasciculate, unequal, 1J or 2 inches 

 long, the longer with interrupted spikelets ; about 1£ liues long, sin- 

 gle or in pairs, one sessile and one pedicelled, obovate, acutish; first 

 glume one-fourth to one third as long as the spikelet, acutish, second 

 and third strongly five to seven nerved, and conspicuously retieulately 

 veined. 



Texas to Arizona. 



11. P. Texan um, Buckley. — Culms stout, 2 to 4 feet high, branching 

 from a decumbent and sometimes rooting base, leafy, smooth ; leaves 

 lanceolate, 4 to 10 inches long, 6 to 12 lines wide, smoothish or scab- 

 rous above and on the margins, sheaths softly and sparsely pubescent, 

 nodes pubescent; panicle (the base generally inclosed in the upper 

 sheath) 4 to 8 inches long, one-half to 1 inch wide, of 5 to 10 erect, rather 

 slender, simple, erect branches, 1 to 3 inches long, closely flowered; 

 rhachis scabrous-pubescent; spikelets single or in pairs, alternate along 

 the angular rhachis, oblong, lanceolate, acute, 2 to 2£ lines long, smooth ? 

 or finely pubescent ; firstglume broadly ovate, half to two-thirds as long 

 as the spikelets, acute, five nerved, second and third glumes equaling 

 the spikelet, strongly five to seven nerved, perfect flower ovate or ob- 

 long-ovate, acutish, transversely wrinkled with fine reticulated striae. 



Cultivated for a forage grass. Texas. 



12. P. Chapmani, Vasey. (P. tenuiculmum. Chap, non Meyer). — Culms 

 filiform, ljto 2i feet high, erect, simple; leaves chiefly radical, linear^ 

 half as long as the culm, about 2 lines wide, upper ones shorter; panicle 

 6 to 12 inches long, of eight to twelve remote, slender, erect spikes, the 



