612 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Figure 1271. — Panicum ramisetum. Two 

 views of spikelet, and floret, X 10. 

 (Type.) 



12 cm long, 2 to 4 mm wide; panicle 5 to 20 cm long; bristle not 



exceeding the spikelet; spikelets about 2.5 mm long, obovate; first 



glume about half as long as the spikelet. 

 91 — Sandy plains and prairies, south- 

 ern Texas and northern Mexico. 



3. Panicum revercboni Vasey. (Fig. 

 1272.) Culms stiffly erect, from short 

 rhizomes, 30 to 70 cm tall; blades erect, 

 stiff, 5 to 20 cm long, 2 to 3 mm wide; 

 panicle 5 to 20 cm long; spikelets mostly 

 one to a branchlet, the bristle equaling 

 or exceeding the spikelet; spikelets 3.5 

 to 3 .8 mm long, elliptic ; first glume about 

 half as long as the spikelet. 91 — 



Rocky or sandy prairies and limestone hills, Texas. 



4. Panicum firmulum Hitchc. and Chase. (Fig. 1273.) Culms 



ascending or decumbent at 



base, 30 to 40 cm tall, 



rather loosely tufted from 



creeping knotted rhizomes 



as much as 5 cm long; 



blades ascending or spread- 

 ing, firm, 4 to 10 cm long, 



4 to 7 mm wide; bristle 1 to 



2 times as long as the spike- 

 let; spikelets 3 to 3.2 mm 



long, obovate; first glume 



half as long as the spikelet. 



91 — Sandy prairies, 



southern Texas. 



Subgenus 2. Dichanthelium 

 Hitchc. and Chase 



Figure 1272. — Panicum reverchoni. Panicle, X 1; two views of 



Perennial, from a crown, spikelet, and floret, x 10. (Type.) 



rarely from short mat- 

 ted rhizomes, surrounded by a more or less well-marked rosette 

 of usually short winter leaves, in spring producing simple 



culms with mostly narrowly 

 lanceolate blades and terminal 

 panicles with numerous spike- 

 lets, these rarely perfecting 

 seed; early culms branching 

 at some or all of the nodes 

 (in a few species from the 

 base only) after the maturity 

 of the primary panicles or 

 sometimes before ; branches 

 often repeatedly branching, 

 the short branchlets more or 

 less fascicled and bearing usu- 

 ally much reduced leaves ; the 

 terminal one or two joints of 

 the primary culm often finally 

 falling, the whole producing an autumnal phase usually strikingly 

 different from the vernal phase; secondary panicles reduced, 



Figure 1273.— Panicum firmulum. Two views of 

 spikelet, and floret, X 10. (Type.) 



