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. BARNYARP 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. long . . . . . . .1. P. capillare. 



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



Spikelets obtuse or barely pointed. 



Leaves smooth above, scabrous beneath; spikelets about 3 mm. long 3. P. Scribnerianum. 



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



rnrn. long 4. P. scoparium. 



1. Panicum capillare L. Sp. PI. 5S. 1753. Culms erect or decumbent, 

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

 hirsute: leaves 15-30 cm. long, 6-10 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. Panicum virgatum L. Sp. PI. 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, (i -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, -1-4.5 mm. long; first 

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

 glume generally longer than the others. ."> -"-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. long, 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. Panicum scoparium Lam. Enc}'cl. 4: 744. 1707. 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, 

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

 spikelets ovate, subacute, 1.5-2, rarely 2.5 mm. long, pubescent. Throughout 

 our 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 



