MANUAL OF THE GRASSES OF THE UNITED STATES 705 



136. PENNISETUM L. Rich. 



Spikelets solitary or in groups of two or three, surrounded by an 

 involucre of bristles (sterile branchlets), these not united except at 

 the very base, often plumose, falling attached to the spikelets; first 

 glume shorter than the spikelet, sometimes minute or wanting; 

 second glume shorter than or equaling the sterile lemma; fertile 

 lemma chartaceous, smooth, the margin thin, enclosing the palea. 

 Annuals or perennials, often branched, with usually flat blades and 

 dense spikelike panicles. Type species, Pennisetum typhoideum L. 

 Rich. (P. glaucum). Name from Latin penna, feather, and seta, 

 bristle, alluding to the plumose bristles of some species. 



The most important species is P. glaucum, pearl millet, which is 

 widely cultivated in tropical Africa and Asia, the seed being used for 

 human food. It has been cultivated since prehistoric times, its wild 

 prototype being unknown. In the United States pearl millet is used 

 to a limited extent in the Southern States for forage, especially for 

 soiling. Two species, P. villosum and P. ruppelii, are cultivated for 

 ornament. An African species, P. purpureum, elephant or Napier 

 grass, is used in the Southern States as a forage plant. 



Plants annual; bristles of involucre about as long as the spikelets. Cultivated. 



1. P. GLAUCUM. 



Plants perennial; bristles much longer than the spikelets. 

 Longer bristles 1 cm long. 



Bristles unlike, the inner silky, plumose 2. P. setosum. 



Bristles all scabrous 3. P. nervosum. 



Longer bristles 3 to 4 cm long, the panicles feathery. 



Panicle oval, tawny 4. P. villosum. 



Panicle elongate, purple or rosy 5. P. ruppelii. 



1. Pennisetum glaucum (L.) R. Br. Pearl millet. (Fig. 1582.) 

 Annual; culms robust, as much as 2 m tall, densely villous below 

 the panicle; blades flat, cordate, sometimes as much as 1 m long 

 and 5 cm wide; panicle cylindric, stiff, very dense, as much as 40 to 

 50 cm long and 2 to 2.5 cm thick, pale, bluish tinged, or sometimes 

 tawny, the stout axis densely villous; fascicles peduncled, spikelets 

 short-pediceled, 2 in a fascicle, 3.5 to 4.5 mm long, obovate, turgid, 

 the grain at maturity protruding from the hairy-margined lemma and 

 palea. (P. typhoideum L. Rich.; Penicillaria spicata Willd.) — 

 Cultivated to a limited extent in the Southern States for forage; 

 Eastern Hemisphere. 



Pennisetum purpureum Schumach. Napier grass. Robust leafy 

 perennial, 2 to 4 m tall; blades elongate, 2 to 3 cm wide; panicle 

 dense, elongate, stiff, tawny or purplish, with sparsely plumose 

 bristles about 1 cm long. % — Introduced from Africa; used as a 

 forage plant in southern Florida; grown in the West Indies and South 

 America. Also called elephant grass. 



2. Pennisetum setosum (Swartz) L. Rich. (Fig. 1583.) Peren- 

 nial ; culms sometimes 30 or more in loose clumps, 1 to 2 m tall, geniculate, 

 sometimes rooting at the lower nodes, bearing 1 to several flowering 

 branches from the lower and middle nodes, scabrous below the panicle; 

 blades elongate, 4 to 18 mm wide ; panicle 10 to 25 cm long, 8 to 10 mm 

 thick, excluding the bristles, rather dense, yellow to purple; fascicles 

 rellexed at maturity; bristles unequal, the outer delicate, mostly 



