28 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
the branchlets bearing 1 to3 short-pediceled spikelets, the setiform prolongation of the 
axis usually about as long as the spikelets, sometimes twice as long; spikelets 3 to 3.2 
mm. long, 1.7 to 1.8 mm. wide, obo- 
vate, subacute, turgid, strongly nerved; 
first glume clasping, half the length 
of the spikelet, pointed, 5 to 7- 
nerved; second glume and _ sterile 
lemma subequal, scarcely covering the 
fruit, 5 to 7-nerved, the glume ob- 
scurely reticulated toward the summit; 
fruit 2.7 to 2.8 mm. long, 1.6 to 1.7 mm. 
wide, obovate-elliptic, abruptly acute, 
very turgid. 
Type U.S. National Herbarium no. 
592755, collected May 27, 1904, Elsordo, Zapata County, Texas, by David Griffiths 
Fis SS hing (no. 6446). 
pare and “4 This species resembles P. ramisetum, from which it differs in the larger spikelets, 
usually longer setze, broader, more or less ciliate blades, and markedly knotty rootstock. 
Fig. 10.—Distributioa of P. firmulum. 
DISTRIBUTION. 
Sandy prairies, southern Texas. 
Texas: Elsordo, Griffiths 6446; Sarita, Hitchcock 3866; without locality, Nealley. 
TRUE PANICUM. 
SYNOPSIS OF GROUPS. 
Inflorescence consisting of several spike-like racemes along a 
main axis; fruit transversely rugose. 
Perennials; online spreading or creeping; spikelets gla- 
[parte SUECCINE aL SESE ee Ne she erch ail os Mulgan sSeMToaE tS he GEMINATA (p. 30). 
Annuals; spikelets pubescent or glabrous...-..--...----- FASCICULATA (p. 35). 
Inflorescence an open or contracted panicle, or if with race- 
mose branches fruit not transversely rugose. 
Annuals; panicles open, usually diffuse. (See also Laxa 
and P. costaricense no. 76.) 
Spikelets glabrous, not warty nor rugulose; fruit pol- 
ished. 
First glume less than one-fourth the length of the 
spikelet, obtuse or truncate; sheaths glab- 
rous except in P. bartowense...-.........-DICHOTOMIFLORA 
wT): 
First glume nearly half the length of the spikelet oes 
or more; sheaths hispid (sometimes glab- 
rous in P. decolorans and P. stramineum)-..CAPILLARIA (p. 54). 
Spikelets warty, rugulose, or hispid; fruit not polished, 
margins of lemma not inrolled. 
Spikelets 2mm. or more long; not tropical species. VERRUCOSA (p. 126). 
Spikelets not over 1.4mm. long; tropical species. TRICHOIDIA (p. 129). 
Perennials (two species in Laxa annuals). 
Fruit transversely rugose (very faintly so in P. ple- - 
num); spikelets ellipsoid, glabrous; plants 
TODUSt | 2220 So an Soe eR ee een ee ee eee Maxima (p. 78). 
Fruit not transversely rugose. 
Spikelets densely silky-villous, 6 to 7 mm. long; 
lemma silky on the margins..........-.-- URVILLEANA (p. 182). 
