44 GRAMINEAE (GRASS FAMILY) 



pairs or panicled. Spikelets oblong to orbicular, flat on the outer surface, con- 

 vex on the inner. Glumes 3, the outer ones membranous, the inner one in- 

 durated and plumose. Grain ovoid or oblong, free. 



1. Paspalum setaceum Michx. Fl. Bor. Am. 1: 43. 1803. Culms mostly 

 erect, 3-6 dm. tall, slender, smooth: sheaths and leaves generally very pu- 

 bescent; the latter 7-20 cm. long, 2-6 mm. wide, erect, acuminate: spikes 

 4-8 cm. long, more or less curved, generally solitary, occasionally 2, on a long- 

 exserted slender peduncle, with usually 1 or 2 additional shorter peduncles 

 from the same upper sheath: spikelets about 1.5 mm. long, in 2 narrow rows, 

 broadly obovate, very obtuse; empty glumes 3-nerved, glabrous or pubescent, 

 third glume obovate, shining. Colorado and eastward. 



7. SYNTHERISMA Walt. 



Annuals, with flat leaves and spikelets borne in pairs or sometimes in threes, 

 in secund spikes which are digitate or approximate at the summit of the culm. 

 Spikes often purplish. Glumes of the spikelet 4, sometimes 3 by the suppres- 

 sion of the lowest one ; the fourth or innermost glume chartaceous, subtending 

 a palet of similar texture and a perfect flower. Stamens 3. Stigmas plumose. 



1. Syntherisma sanguinalis (L.) Dulac. Fl. Hautes-Pyr. 77. 1867. Culms 

 3-8 dm. high, becoming prostate at base and rooting at -the lower nodes: 

 lower sheaths densely papillose-hirsute: leaves 4-20 cm. long, 4-10 mm. wide, 

 more or less papillose-hirsute on both surfaces: racemes 3-10, 5-18 cm. long: 

 spikelets 25-30 mm. long and about 0.8mm. wide, elliptic-lanceolate, acute, in 

 pairs, the first glume minute, triangular, the second 3-nerved, about one half 

 as long as the spikelet, the third 7-nerved, the fourth yellowish- white, acutely 

 apiculate. Panicum sanguinale. CRAB GRASS. Generally introduced in fields 

 and waste grounds. 



8. BRACHIARIA Ledeb. 



Annuals or perennials with flat leaves and a panicle composed of alternate 

 scattered one-sided racemes with the spikelets borne in 2 rows. Spikelets 

 1-flowered, articulated to the pedicel below the glumes. Glumes 4, the outer 

 3 membranous, the fourth chartaceous, inclosing a palet of similar texture 

 and a perfect flower. Stamens 3. Styles distinct; stigmas plumose. Grain 

 free. Panicum in part. 



1. Brachiaria obtusa (H.B.K.) Nash, Brit. Man. 77. 1901. Glabrous 

 stoloniferous perennial, the culms 3-6 dm. high, simple or branching at base: 

 leaves 6-22 cm. long, 2-6 mm. wide, usually erect, long-acuminate: panicle 

 5-15 cm. long, composed of 3-5 erect racemes 18-37 mm. long: spikelets about 

 3 mm. long, crowded, oval or obovoid, obtuse, turgid; first glume shorter than 

 the rest, obtuse, 5-nerved; second, third and fourth glumes about equal, the 

 second and third 5-nerved, the fourth chartaceous. Colorado and southward. 



9. ECHINOCHLOA Beauv. 



Commonly annuals with broad leaves and a terminal inflorescence consist- 

 ing of one-sided racemes racemosely or paniculately arranged. Spikelets 

 ] -flowered, singly disposed, or in smaller racemes or clusters on the ultimate 

 divisions of the inflorescence. Glumes 4, the outer 3 membranous, hispid on 

 the nerves, the third and usually also the second awned or sometimes merely 

 awn-pointed, the awn often very long; fourth glume indurated, shining, 

 frequently pointed, inclosing a palet of similar texture and a perfect flower. 

 Stamens 3. Styles distinct; stigmas plumose. Grain free. Panicum in part. 



1. Echinochloa Crus-galli (L.) Beauv. Agros. 53. 1812. Annuals, 4-12 dm. 

 high, the culms often branching at base: sheaths smooth and glabrous: leaves 



