POACEAE 93 



to linear-lanceolate, glabrous, or sometimes pubescent, the primary ones 3-8 cm. long, 4-7 

 mm. wide, those on the brandies smaller : panicle at first included at tlie base, finally ex- 

 serted, as broad as or broader than long, the branches very long and finally spreading : 

 spikelets on pedicels many times their length, elliptic, 2.5-3 mm. long and about 0.8 mm. 

 wide, glabrous or pubescent. [P. autmnnale Bosc. ] 



In dry places, South Carolina to Minnesota, Florida, Texas and Arizona. Spring and fall. 



26. Panicum capillarioides Vasey. Perennial. Stems tufted, erect, or geniculate 

 at the base, pubescent with spreading hairs, at least below : leaf-blades erect or ascending, 

 linear, glabrous, or sparingly pubescent, 2 dm. long or less, 3-5 mm. wide : panicle 1-1.5 

 dm. long, its branches long and ascending : spikelets lanceolate, acuminate, 6 mm. long, 

 glabrous. 



In dry soil, southern Texas. Summer. 



27. Panicum halophilum Nash. Stems from a long stout rootstock, 1.5-4 dm. tall : 

 leaves numerous, crowded at the base of the stem ; sheaths overlapping, the margins some- 

 times ciliate ; blades spreading, lanceolate, usually 2-6 cm. long, sometimes longer, 3-8 

 mm. wide : panicle dense, 2-9 cm. long, its branches ascending : spikelets crowded, gla- 

 brous, about 2.5 mm. long, the first scale h as long as the spikelet, or nearly so, the apex 

 acute at a broad angle, apiculate. 



In sand along the seashore, Mississippi. Also in Mexico. Spring to fall. 



28. Panicum ripens L. Stems 3-8 dm. tall, from long stout rootstocks : leaf-sheaths 



overlapping, at least at the base, the lower ones at first densely hirsute, later sometimes 



glabrate ; blades erect to spreading, 1.5 dm. long or less, 3-6 mm. wide : panicle 6-15 cm. 



long, narrow and confined, slender, its branches erect or ascending : spikelets yellowish or 



green, glabrous, 2.5 mm. long, the first scale about \ as long as the spikelet, truncate at 



the apex. 



In sand along the seashore, Alabama, Mississippi, and California. Of wide geographic distribu- 

 tion. Summer and fall. 



29. Panicum amarum Ell. Smooth and glabrous, glaucous. Stems arising from long 

 branching rootstocks, 3-9 dm. tall : leaf-sheaths overlapping ; blades 1.5-3 dm. long, 6-12 

 mm. wide, long-acuminate, thick and leathery, involute on the margins, at least toward 

 the apex : panicle linear, less than 3 dm. long, its branches erect : spikelets 5-6 mm long. 



On sea beaches. New Hampshire to Florida. Fall. 



30. Panicum virgatum L. Glabrous. Stems erect from a stout rootstock, 9-15 

 dm. tall : leaf-l)lades elongated, 3 dm. long or more, 6-12 mm. wide, flat, glabrous or pu- 

 bescent : panicle 1.5-5 dm. long, its branches widely spreading or sometimes nearly erect : 

 spikelets ovate, acuminate, 4-4.5 mm. long, glabrous. 



In moist or dry soil, Maine and Ontario to Minnesota, Florida and Texas. Summer and fall. A 

 variety, known as P. virgatum brevirarnosum Nash, with short spreading branches and smaller spikelets, 

 occurs in eastern Georgia. Switch Grass. 



31. Panicum mdximum Jacq; Stem 1-2 m. tall or more, leafy : leaf-sheaths over- 

 lapping, glabrous, or tuberculate-pubescent ; blades 2-8 dm. long or more, 1-4 cm. wide, 

 glabrous : panicle 3-6 dm. long, its branches erect or nearly so, very long : spikelets gla- 

 brous, 3-4 mm. long, the fourth scale transversely rugose. 



In fields and along roadsides, Georgia and Florida to Texas. Introduced from tropical America. 

 Summer and fall. 



32. Panicum agrostoides Muhl. Stems 4-8 dm. tall, much branched, compressed : 

 leaf-blades 3 dm. long or more, 4-8 mm. wide : panicle pyramidal, 1-3 dm. long, its 

 branches spreading : spikelets 1.5-2 mm. long, acute, straight. 



In wet ground, Maine to Missouri, Florida and Texas. Summer and fall. 



33. Panicum cond^nsum Nash. Stems 6-10 dm. tall, branched, the lateral panicles 

 often much exserted : leaf-blades 2-4 dm. long, 6-8 mm. wide, erect : panicle dense, 1-2 

 dm. long, contracted, its branches erect : spikelets numerous, about 2 mm. long, glabrous, 

 acute. 



In ditches and wet places, South Carolina to Florida. Fall. 



34. Panicum Combsii Scribn. & Ball. Glabrous. Stems tufted, erect, slender, finally 

 branched, 4-6 dm. tall : leaf-sheaths compressed, keeled ; blades erect, linear, acuminate, 

 5-15 cm. long, 2-3 mm. wide : panicle about 1 dm. long, its branches finally spreading : 

 spikelets 3 mm. long, lanceolate, acute. 



In damp or wet woods, Florida. Summer and fall. 



35. Panicum pseudanceps Nash. Glabrous. Stems tufted, 3-7 dm. tall, erect, 

 slender, compressed, finally branching at each node : leaf-sheaths compressed and keeled, 

 an external tuft of long hairs on each side at the apex ; ligule a ring of hairs 2-3 mm. 

 long ; blades 1-3 dm. long, 2-4 mm. wide, somewliat pilose on the upper surface near the 



