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



naked at base, the branchlets more or less appressed; spikelets 3 

 mm long, 1 mm wide. 01 — Low moist ground, southern Texas; 

 tropical America. 



136. Panicum hirsutum Swartz. (Fig.^ 1504.) Culms robust, 

 erect, as much as 1.5 m tall and 1 cm thick, simple or branched at base 

 only; nodes appressed-pubescent ; sheaths papillose-hirsute, the hairs 

 stiff, spreading, fragile, causing mechanical irritation to the skin when 

 handled; blades flat, as much as 60 cm long and 3.5 cm wide, glabrous; 

 panicle 20 to 35 cm long, at first condensed, finally open, the branches 

 ascending; spikelets 2 to 2.2 mm long. 01 

 — Open moist ground, southern Texas; tropical 

 America at low altitudes. 

 7. Maxima. — Tall robust perennials; ligules 

 membranaceous, ciliate; blades linear, 

 flat; panicles large, many-flowered; 

 spikelets ellipsoid, faintly nerved, gla- 

 brous; fruit transversely rugose. 

 137. Panicum maximum Jacq. Guinea 

 grass. (Fig. 1505.) Plants light green, in 

 m ghies- lar g e bunches from short stout rhizomes ; culms 



breghtii. 

 and floret 



two' views of spikeiet, mostly erect, the nodes usually densely hirsute ; 

 sheaths papillose-hirsute to glabrous, usually 

 densely pubescent on the collar; ligule 4 to 6 mm long; blades 30 

 to 75 cm long, as much as 3.5 cm wide, glabrous, very scabrous on 

 the margins, sometimes hirsute on the upper surface near the base; 

 panicles 20 to 50 cm long, about one-third as wide, the long rather 

 stiff branches ascending, naked at base, the lower in whorls, the axils 

 pilose, the branchlets short, appressed, bearing more or less clustered 

 short-pediceled spikelets; spikelets 3 to 3.3 mm long; first glume 

 about one-third the length of the spikeiet. 01 — Fields and waste 

 places, southern Florida, and southern Texas, 

 introduced from Africa; tropical regions of 

 both hemispheres at low altitudes. Guinea 

 grass is the most important cultivated forage 

 grass of tropical America. It grows in 

 moderately dry ground and can be used for 

 pasture or for soiling. Much of the green feed 

 cut for forage is this species. 



138. Panicum plenum Hitchc. and Chase. 

 (Fig. 1506.) Plants mostly in large clumps, 

 mostly glaucous, from a stout rhizome; culms 

 1 to 2 m tall, erect from a usually decumbent base, compressed; 

 sheaths glabrous, somewhat keeled; blades 20 to 35 cm long, 7 to 17 

 mm wide, glabrous or nearly so; panicle 20 to 50 cm long, open; 

 spikelets 3 to 3.4 mm long. 01 — Moist places in rocky hills and 

 canyons, Texas to Arizona; Mexico. Differs from P. bulbosum in the 

 absence of the basal corm. 



139. Panicum bulbosum H.B.K. Bulb panicum. (Fig. 1507.) 

 Culms in tufts, 1 to 2 m tall, erect, the lowest internode thick- 

 ened to a hard cormlike base 1 to 2 cm thick, budding at base, some- 



Figure 1504.— Panicum hirsu- 

 tum. Two views of spikeiet, 

 and floret, X 10. (Type.) 



