64 POACEAE 



beneath, rough above and somewhat hirsute near the base : racemes in pairs, exserted, or a 

 little included in the narrow spathes, 2-3 cm. long : sessile spikelet 3-4 mm. long, exceed- 

 ing the internode, the awn 1-1.5 cm. long, more or less contorted, slightly twisted at the 

 base ; pedicellate spikelet wanting, or a minute rudimentary scale, the pedicel considerably 

 exceeding the sessile spikelet. 



In sandy soil, Florida to Mississippi. Fall. 



17. Andropogon arctatus Chapm. Stems 1-1.5 m. tall, branched toward the sum- 

 mit, the branches in l's-3's : leaf -sheaths, at least the lower ones, more or less densely 

 appressed-hirsute at the summit ; blades erect, 3 dm. long or less, 5 mm. wide or less, the 

 upper surface rough, the lower usually densely appressed-hirsute toward the base : racemes 

 in pairs, rarely in 3's or 4's, rather stout, dark gray, 2.5-4 cm. long, long-exserted : sessile 

 spikelet 5-6 mm. long, about twice as long as the internode, the awn more or less con- 

 torted, 1-1.5 cm. long ; pedicellate spikelet usually present, consisting of a single scale, the 

 pedicel considerably "shorter than the sessile spikelet. 



In low pine lands, Florida. Fall. 



18. Andropogon argyrafeus Schult. Stems tufted, 8-12 dm. tall, about twice as long 

 as the basal leaves, the branches in l's-3's : leaf-sheaths smooth or rough, glabrous or 

 hirsute ; blades 3 dm. long or less, 3 mm. wide or less, rough : racemes in pairs, rather 

 stout, silvery gray, 3-5 cm. long, long-exserted, the hairs on the summit of the internodes 

 1^-2 times their length : sessile spikelet 5-6 mm. long, about twice ^as long as the inter- 

 node, the first scale appressed-pubescent between the nerves, acuminate from about the 

 lower third, nerveless between the keels and usually deeply depressed, the awn more or 

 less contorted, 1.5-2.5 cm. long ; pedicellate spikelet of a single scale, 1-3 mm. long, the 

 pedicel usually a little shorter than the sessile spikelet. 



In dry soil, Delaware and Maryland to Florida, and Texas; also in Indian Territory and Mis- 

 souri, and probably southward to the Gulf. Fall. SILVER BEARD. 



19. Andropogon Cabanisii Hack. Stems 6-10 dm. tall, the branches in 1's or 2's : 

 leaf -sheaths smooth or a little roughened ; blades 2.5 dm. long or less, 2-4 mm. broad, 

 smooth beneath, rough above : racemes in pairs, 4-7 cm. long, grayish, the hairs at the 

 apex of the internodes as long as or a little exceeding them, rather scant : sessile spikelet 

 6-7 mm. long, broadly lanceolate, tapering from the middle, about twice as long as the 

 internode, the first scale strongly hispidulous and 2-3-nerved between the keels, the nerves 

 running the entire length of the scale ; pedicellate spikelet of a single hispidulous scale 

 3-3.5 mm. long, the pedicel about f as long as the sessile spikelet. 



In dry soil, Pennsylvania (according to Hackel) and Florida. Summer. 



20. Andropogon Scribnerianus Nash. Glaucous. Stems tufted, 3-10 dm. tall, 

 twice as long as the basal leaves, rather sparsely branched above : leaf-sheaths shorter than 

 the internodes, smooth and glabrous ; blades 1 dm. long or less, 2.5 mm. wide or less, the 

 upper surface minutely pubescent and also often hirsute near the base : racemes in pairs, 

 stout, long-exserted, 4-7 cm. long, bright silvery white, the hairs on the internodes copious, 

 those at the summit about twice the length of the internodes : sessile spikelet 5-6 mm. 

 long, about twice as long as the internode, the first scale narrowed from about the middle, 

 glabrous and shining between the keels, the internerve flat or nearly so, the awn of the 

 fourth scale more or less contorted and bent, somewhat twisted below, 1-1.5 cm. long ; 

 pedicellate spikelet wanting, or present as a small scale 1.5 mm. long or less, the pedicel 

 equalling or a little shorter than the sessile spikelet. 



In dry pine lands, Georgia and Florida. Spring and summer. 



21. Andropogon furcatua Muhl. Stems 1-2 m. tall : leaf-sheaths glabrous or some- 

 times slightly hirsute ; blades 6 dm. long or less, 12 mm. wide or less, smooth beneath and 

 glabrous or rarely a little hirsute, more or less roughened above and hirsute at the base : 

 racemes in 2's-6's, 5-10 cm. long, stout, long-exserted, the hairs of the internodes and 

 pedicels grayish white, 1-2 mm. long : sessile spikelet 7-10 mm. long, the outer 2 scales 

 more or less hispidulous, the awn 7-15 mm. long, geniculate, twisted at the base ; pedicel- 

 late spikelet as large as or a little smaller than the sessile, staminate, awnless. 



In dry or moist soil, Maine and Ontario to Manitoba, Florida, Kansas and Texas. Summer and 

 fall. 



22. Andropogon chrysocomus Nash. Stems 7-15 dm. tall, the branches in 

 l's-3's : leaf -sheaths smooth and glabrous ; blades 3 dm. long or less, 7 mm. wide or less, 

 smooth beneath, a little roughened above : racemes in 2's-4's, 5-9 cm. long, stout, long- 

 exserted, the hairs of the internodes and pedicels about 3 mm. long, usually yellow : ses- 

 sile spikelet about 1 cm. long, with a basal ring of short hairs, the outer 2 scales hispid on 

 the nerves, the awn of the fourth scale twisted at the base, geniculate, 10-12 mm. long ; 

 pedicellate spikelet awnless. 



In dry soil, Kansas to Texas. Summer and fall. 



