GRAMINEAE (GRASS FAMILY) 45 



15-60 cm. long, 6-25 mm. wide, smooth or scabrous: panicle composed of 

 5-15 sessile, erect or ascending branches, or the lower branches spreading or 

 reflexed: spikelets ovate, green or purple, densely crowded in 2-4 rows on one 

 side of the rachis; second and third glumes about 3 mm. long; scabrous or 

 hispid, the second awnless or with a long rigid awn, the third awnless or short 

 awned, the fourth ovate, abruptly pointed. Babntakd Grass. — Introduced 

 in fields and waste grounds. 



10. PANICUM L. Panic Grass 



Annuals or perennials, various in habit, with open or contracted panicles. 

 Spikelets 1-2-flowered, when 2-flowered the lower one staminate. Glumes 4, 

 the 3 lower membranous, empty, or the third with a staminate flower, varying 

 in the same species; the inner or fourth glume chartaceous, shining, inclosing 

 a palet of similar texture and a perfect flower; awns none. Stamens 3. 

 Styles distinct; stigmas plumose. Grain free, inclosed in the hardened fruit- 

 ing glume and palet. 



Spikelets acuminate. 



Annual; spikelets 2-2.5 mm. Ions 1. P. capillare. 



Perennial; spikelets 4-4.5 mm. long 2. P. virgatum. 



Spikelets obtuse or barely pointed. 



Leaves smooth abov^e, scabrous beneath; spikelets about 3 mm. long 3. P. Scribnerianum. 



Leaves more or less pubescent on both surfaces; spikelets 1.5-2.5 



mm. long 4. P. scoparium. 



1. Panicum capillare L. Sp. PI. 58. 1753. Culms erect or decumbent, 

 3-6 dm. tall, simple or sometimes sparingly branched: sheaths papillose- 

 hirsute: leaves 15-30 cm. long, 6-16 mm. wide, pubescent: panicles widely 

 spreading, capillary, the terminal one 20-25 cm. long; the lateral panicles, 

 when present, smaller: spikelets 2-2.5 mm. long, acuminate; first glume one 

 fourth to one half as long as the spikelet; second and third glumes nearly 

 equal, very acute; the fourth 1.5 mm. long. Witch Grass. — ^Dry soil; a weed 

 in cultivated fields. 



2. PanicumvirgatmnL. Sp.Pl. 59. 1753. Stout, erect, glabrous, perennial, 

 9-15 dm. high, usually forming large tufts, with strong creeping rootstocks: 

 leaves elongated, 3 dm. long or more, 6-12 mm. wide, flat, long-acuminate, 

 narrowed toward the base, glabrous, rough on the margins: panicle 15-50 cm. 

 long, the lower branches 10-25 cm. long, more or less widely spreading or 

 sometimes nearly erect: spikelets ovate, acuminate, 4-4.5 mm. long; first 

 glume acuminate, about one half as long as the spikelet, 3-5-nerved; second 

 glume generally longer than the others, 5-7-nerved; the third similar and 

 usually subtending a palet and staminate flower. Switch Grass. — Sandy river 

 bottoms; extending into our range from the eastern United States. 



3. Panicum Scribnerianum Nash, Bull. Torr. Bot. Club 22: 421. 1895. 

 Perennial, 2-4 or more dm. high: culms erect, finally branching, sparingly 

 pubescent: sheaths usually papillose-pilose: leaves more or less spreading, 

 flat, smooth above, scabrous beneath, 5-10 cm. Jong, 6-12 mm. wide: panicles 

 small, ovoid, 3-7 cm. long: spikelets turgid, obovoid,.obtusish, about 3 mm. 

 long, sparsely pubescent or nearly glabrous. — ^Throughout our range. 



4. Panicma scoparium Lam. Encycl. 4: 744. 1797. Perennial, 1-4 or more 

 dm. high: culms erect or ascending and finally more or less branched, usually 

 densely pubescent with spreading hairs as also the sheaths, the nodes bearded 

 and with a glabrous ring immediately below: leaves more or less softly pubes- 

 cent on both surfaces and often somewhat villous, scabrous on the margins, 



>-15 cm. long, 5-10 mm. wide: panicles ovoid or subpyramidal, 4-7 cm. long: 

 pikelets ovate, subacute; 1.5-2, rarely 2.5 mm. long, pubescent. — ^Throughout 

 rur range. 



11. CHAETOCHLOA Scribn. 



Annuals or perennials with erect culms, few leaves, and bristly spike-like 

 panicles. Spikelets 1-flowered, or rarely with a second staminate flower, the 



