MANUAL OF THE GRASSES OF THE EXITED STATES 



661 



molle (Vasey) Hitchc. and Chase. Differing from P. boscii in the 

 downy-villous culms and sheaths and the velvety blades. % — 

 About the same range as the species. 



Subgenus 3. Eupaxicum Godr. 



Spikelets in open or condensed panicles or in spikelike racemes, the 

 branchlets not produced as bristles (the naked tip forming a short 

 point in Geminata) ; not presenting vernal and autumnal phases 

 of a distinctive character, with winter rosettes of leaves different 

 from the culm leaves. 



1. Geminata. — Subaquatic glabrous perennials; inflorescence of sev- 



eral erect, spikelike racemes distant on an elongate axis; rachis 

 ending in a short naked point; spikelets subsessile, abruptly 

 pointed, glabrous, first glume truncate; fruit transversely 

 rugose. 



111. Panicum geminatum Forsk. (Fig. 1468.) Culms tufted, 25 

 to 80 cm tall, scarcely succulent, often decumbent at base or with 

 stolons rooting at the nodes; blades 10 to 20 cm long, 3 to 6 mm wide, 

 flat, or involute toward the apex; panicle 12 to 30 cm long, the 

 appressed racemes 12 to 18, the lower 2.5 to 3 cm long, the upper 

 gradually shorter; spikelets 2.2 to 2.4 mm long, 5-nerved. % ■ — Moist 

 ground or shallow water, mostly near the coast, southern Florida, 

 Louisiana, and Texas; warmer regions of both hemispheres. 



112. Panicum paludivagum Hitchc. and Chase. (Fig. 1469.) 

 Resembling P. geminatum, but the culms elongate from a long creeping 

 rooting base, rather succulent, as much 

 as 2 m long, the lower part submerged, 

 loosely branching; blades 15 to 40 cm 

 long, scabrous on the upper surface; 

 spikelets 2.8 to 3 mm long, faintly 

 3-nerved; fruit obscurely rugose. % 

 — More or less submerged in fresh- 

 water rivers and lakes, Florida, Texas; 

 Mexico, Guatemala. 



2. Purpurascentia. — Stoloniferous ro- 



bust perennial; a single species 

 introduced. 



113. Panicum purpurascens Raddi. 

 Para grass. (Fig. 1470.) Culms decumbent and rooting at base, 

 2 to 5 m long, the nodes densely villous; sheaths villous or the upper 

 glabrous, densely pubescent on the collar; blades 10 to 30 cm long, 

 10 to 15 mm wide, flat, glabrous; panicle 12 to 20 cm long, the 

 rather distant subracemose densely flowered branches ascending or 

 spreading; spikelets subsessile, 3 mm long, elliptic, 5-nerved, glabrous; 

 fruit minutely transversely rugose. % (P. barbinode Trin.) — Culti- 

 vated and waste ground in moist soil, borders of rivers, marshes, and 

 swamps, Florida, Alabama (Mobile), Texas; Oregon (Linn ton); 

 throughout tropical America at low altitudes. Commonly cultivated 

 in tropical America as a forage grass, being cut for green feed. It 

 probably was introduced into Brazil at an eary date from Africa. 



3. Fasciculata. — Branching annuals; blades flat; ligules not more than 



1 mm long; panicles of ascending spikelike racemes along an 

 angled axis; spikelets subsessile, abruptly pointed strongly 5- to 

 7-nerved; fruit transverse!}' rugose. 



Figure 1469.— Panicum paiudivagum. Two 

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



