Abundant in moist or poorly drained areas, in wet meadows, on muddy banks 

 of ponds, lakes and streams, in shallow water of ponds and lakes, swampy areas 

 and along sloughs, in Okla. (McCurtain, Adair, Atoka, LeFlore, Osage and 

 Mayes cos.) and e. and s.e. Tex., infrequent w. to n.-cen. Tex., late summer-fall; 

 most of e. U.S.; W.I.; Coah. 



17. Panicum tenerum Beyr. Fig. 161. 



Perennial from knotty crowns; culms several, subcompressed, wiry, erect, 4-9 

 dm. tall; lower sheaths pubescent toward the summit, with spreading hairs; ligule 

 minute; blades 4-15 cm. long, 2-4 mm. broad, erect, firm, subinvolute, pilose on 

 upper surfaces toward the base; panicle 3-8 cm. long, very slender, terminal and 

 axillary; spikelets short-pedicelled (the pedicel usually with a few long hairs), 

 2.2-2.8 mm. long, pointed, glabrous; fertile lemma and palea smooth and shiny. 



Rare in wet places, margins of swamps and wet places in pine barrens, in 

 s.e. Tex., rarer still in e. Tex., summer-fall; Coastal States, N.C. to Tex.; W.I. 



18. Panicum amanilum Hitchc. & Chase. Beach panic. Fig. 154. 



Perennial from extensive decumbent subrhizomatous to rhizomatous bases, 

 forming clumps as much as 3 m. across; ascending aerial portions of the numerous 

 culms to 1 m. long and 1 cm. thick, glaucous, glabrous throughout; ligule a fringe 

 about 2 mm. long or at the extreme base of the fringe a firm minute scale; 

 blades linear, firm, 2-5 dm. long, 5-12 mm. broad, involute near the tip, pilose 

 on the upper surface near the base; panicle large, rather compact, 3-10 cm. 

 broad, slightly nodding, densely flowered; spikelets 4.3-5.5 mm. long, acuminate- 

 pointed, glabrous; sterile lemma strongly 5- to 9-nerved; lower floret staminate; 

 fertile lemma and palea smooth and shiny. 



All along the Gulf beaches in loose dune sand, also on margin of swamps and 

 wet places in pine barrens, fall; beaches, N.J. to Mex.; W.I. 



Very doubtfully distinct from P. amarum Ell., which occurs on beaches from 

 Connecticut to Georgia, and has been reported to occur in Texas. P. ainanim 

 supposedly differs in more definitely rhizomatous habit, with culms rising singly 

 at intervals, panicle a fourth to a third the entire height of the plant and not 

 more than 3 cm. broad and spikelets 5-6.5 mm. long. 



Panicum amanilum intergrades with P. virgatum inland. 



19. Panicum virgatum L. Switchgrass. Fig. 162. 



Perennial from strong branching scaly horizontal rhizomes; culms stout, robust, 

 in large bunches, green or glaucous, tough, 1-2 (-3) m. tall; sheaths glabrous; 

 ligule membranous, ciliate; blades 1-6 dm. long, 3-15 mm. broad, flat, glabrous or 

 sometimes pilose above near base, rarely pilose all over; panicle 15-50 cm. long, 

 open and diffuse; spikelets turgid, often gaping, glabrous, (2.8-) 3.5-5 mm. long, 

 acuminate-pointed; first glume clasping, two thirds to three fourths as long as the 

 spikelet, acuminate or cuspidate; sterile lemma 5- to 9-nerved; lower floret usually 

 staminate; fertile lemma narrowly ovate, smooth and shiny, the margins inrolled 

 only in the lower part. 



In moist or seasonally moist open places, fresh or brackish marshes, seepage 

 areas, swamps about lakes, edge of ponds and in shallow water of pools, in Okla. 

 (Ottawa, Woodward, Creek, LeFlore and McCurtain cos.), nearly throughout 

 Tex. but infrequent or rare in the Trans-Pecos, and N. M. (Colfax, Guadalupe 

 and Quay cos.), late summer-fall; N.S. and Ont. to N.D. and Wyo., s. to Gulf 

 States; Cuba; reported in Jal. and Gro. but perhaps based on misdeterminations; 

 reports of its occurrence in Coah. and Chih. are based on specimens of P. bulbo- 

 sum. 



320 



