12 POACEAE. 



1. T. dactyloides L. Steins 1-3 m. tall : leaf -blades 6 dm. long or less, 1-4 cm. 

 wide: spikes in 2's-4's, 1-3 dm. long: pistillate spikelets 7-10 mm. long; stami- 

 nate spikelets 7-10 mm. long. Lower Susquehanna valley. Bather rare, on 

 river banks and islands. Schists. Spr. GAMA-GRASS or SESAME-GRASS. 



2. SCHIZACHYRIUM Nees. Annual or perennial grasses, tufted, or from 

 rootstocks 7 with flat or involute leaf -blades, and spike-like racemes, singly dis- 

 posed, terminating the stem or its branches. Spikelets in pairs at each node of 

 the articulated and frequently hairy rachis, one sessile, the other pedicellate. 

 Sessile spikelet of 4 scales, the outer 2 indurated, sometimes pubescent, the 

 remainder of the scales hyaline, the fourth scale entire or 2 -toothed at the apex, 

 bearing a straight, contorted or spiral awn; palet small, hyaline. Pedicellate 

 spikelet sterile, of 1 or 2 scales, or wanting. Stamens 1-3. Styles distinct. 



1. S. scoparium (Michx.) Nash. Plants green or purplish, sometimes glaucous. 

 Stems tufted, 4.5-15 dm. tall : leaf -blades 5 dm. long or less, 8 mm. wide or less : 

 racemes 3-6 cm. long: sessile spikelet 5-7 mm. long, the awn geniculate, 8-15 

 mm. long; pedicellate spikelet 2-4.5 mm. long. Common, in old fields and on 

 roadsides. -Sum. and fall. BROOM-GRASS. BEARD-GRASS. 



3. ANDROPOGON [Eoyen] L. Perennial grasses, tufted or from elongate 

 rootstocks, with flat or involute leaf -blades, and spike-like racemes, disposed in 

 pairs or sometimes in 3 's or more, terminating the stem or its branches, and 

 often protruding from the side of a membranous spathe-like sheath. Spikelets 

 sometimes with a ring of short hairs at the base, in pairs at each node of the 

 articulated and frequently hairy rachis, one sessile, the other pedicellate. Sessile 

 spikelet of 4 scales, the outer 2 indurated, often pubescent, the remainder of the 

 scales usually hyaline, the fourth scale entire or 2-toothed at the apex, bearing a 

 straight contorted or spiral awn, or sometimes awnless; palet small, hyaline. 

 Pedicellate spikelet usually sterile, of 1 or 2 scales, sometimes of four scales and 

 enclosing a staminate or more rarely a perfect flower, or frequently entirely 

 wanting, the first scale rarely short-awned. Stamens 1-3. BEARD-GRASS. 

 BROOM-GRASS. SAND-GRASS. 



Pedicellate spikelet much smaller tban the sessile one, sterile, with 1 or 2 scales. 

 Inflorescence with its branches many times divided, the lower ones elongate, 

 thus forming a corymbiform mass or masses : upper stem-leaves usually ex- 

 ceeding the inflorescence. 1. A. corymbosus. 

 Inflorescence with its branches not much divided and the 

 lower branches not excessively elongate, hence long and 

 narrow : upper steml-leaves usually shorter than the 

 inflorescence. 2. A. virginicus. 

 Pedicellate spikelet as large as the sessile one or larger, con- 

 sisting of 4 scales, with a staminate flower, or rarely a per- 

 fect flower. 3. A. furcatus. 



1. A. corymbosus (Chapm.) Nash: Stems 4-10 dm tall: stem-leaves with blades 

 3 dm. long or less, 5 mm. wide or less, rough: spathes very rough, tightly en- 

 rolled around the peduncle : racemes in pairs, 2-3 cm. long : sessile spikelet 4-5 

 mm. long, the awn 12-13 mm. long; pedicellate spikelet usually present as a 

 subulate scale. N. M. Eather rare, mostly in swamps. Pall. 



2. A. virginicus L. Stems tufted, 5-10 dm. tall: leaf -blades 4 dm. long or less, 

 2-5 mm. wide: spathes 3-5 cm. long, extending beyond the racemes: racemes in 

 pairs, 2-3 cm. long: sessile spikelet 3-4 mm. long, the awn straight, 10-15 mm. 

 long; pedicellate spikelet wanting, or rarely present as a minute scale. Eather 

 common, especially in old fields. Fall. 



3. A. furcatus Muhl. Stems 1-2 m. tall : leaf -blades 6 dm. long or less, 12 mm. 

 wide or less: racemes in 2*8^6*8, 5-10 cm. long: sessile spikelet 7-10 mm. long, 



