GRASS FAMILY. 39 



Panicle usually 1-3 era. thick; bristles usually purple; spikelets 2.5-3 mm. long. 



3. C. italica. 

 Second glume manifestly shorter than the lemma; perennials. 4. C. composita. 



1. C. glauca (L.) Scribn. Erect or ascending, glaucous annual; stem 3-12 

 dm. high, branching at the base, glabrous, compressed; leaf-blades 5-15 cm. 

 long, 4-8 mm. wide, glabrous or with scattered long hairs at the base; spikelet 

 broadly ovate, 3 mm. long; second glume one-half to two-thirds as long as the 

 spikelet, ovate, acute; third glume equalling the lemma, which is broadly ovate, 

 striate, transversely rugose. Setaria glauca Beauv. Waste places and cultivated 

 ground: X.S. Fla. Tex. Colo. Sask.; naturalized from Eurasia. Plain- 

 Submont. Je-S. 



2. C. viridis (L.) Scribn. Erect glabrous annual; stem 2-9 dm. high, branched 

 at the base, compressed; leaf-blades 5-25 cm. long, 4-10 mm. wide, long-acumin- 

 ate, slightly scabrous on both sides; bristles slen-cler, scabrous, 1-1.5 cm. long, 

 green or rarely purplish; lemma elliptic, finely and faintly wrinkled below or 

 only striate. S. viridis Beauv. Waste places and cultivated ground : Xewf. 

 Fla'. Calif. B.C.; Mex.; naturalized from Eu. Plain Submont. Jl-S. 



3. C. italica (L.) Scribn. Stout, erect, somewhat glaucous annual; stem 

 simple or branched at the base, 5-20 dm. high, glabrous; nodes bearded; leaf- 

 blades lanceolate, 2-4 dm. long, 1.5-3 cm. wide, scabrous on both sides; bristles 

 green or purplish, 3-10 cm. long, scabrous; lemma smooth or faintly trans- 

 versely rugose, striate. S. italica Beauv. Waste places and fields; escaped from 

 cultivation: Que. Fla. 'Tex. 'Colo. S.D.; native of Eurasia. Jl-S. 



4. C. composita (H.B.K.) Scribn. Pale, glaucous perennial; stem geniculate 

 and branched at the base, subcompressed, scabrous or pubescent especially below 

 the nodes; blades linear, plane, 1-2.5 dm. long, 2-5 mm. wide, glaucous, scabrous 

 on both sides; panicle pale-green, loose, interrupted below: bristles usually single 

 below each spikelet, flexuose, 5-15 mm. long, scabrous; spikelets narrowly ovate, 

 2-3 mm. long; lemma striate, smooth, obscurely transversely wrinkled below. 

 S. composita H.B.K. Hills, plains, and canons: Tex. Colo. Ariz.; Mex., 

 and S. Am. Son. Je-O. 



13. CENCHRUS L. BUR-GRASS, SANDBUR, SANDSPUR. 



Annuals or perennials. Spikes terminal. Spikelets 2-6, in an ovate or glo- 

 bose involucre, consisting of two thick hard valves, which are exteriorly armed 

 with stout spines at the base, the involucres articulated to the rachis and readily 

 deciduous, carrying the persistent spikelets with them. The first and second 

 glumes empty, the first small or minute, the third equalling or longer than the 

 second, enclosing a palet and also sometimes a st animate flower, the lemma 

 chartaceous, firmer, enclosing a palet of similar texture and a perfect flower. 

 Stamens 3. Styles often connate at the very base; stigmas plumose. 



1. C. carolinianus Walt. Erect or decumbent annual; stem 2-9 dm. long, 

 branching; leaf-sheaths usually loose, compressed, smooth; blades 6-12 cm. long, 

 4-8 mm. wide, smooth or rough; spikes 3-6 cm. long, sometimes partly included; 

 involucres 6-20, enclosing each 2 spikelets, 3-5 mm. broad, pubescent; spines 

 3-4 mm. long; spikelets 6-7 mm. long, usually exserted beyond the involucre. 

 C. tribuloides Auth.,not L. Sandy banks and waste places, sometimes becom- 

 ing a noxious weed: Me. Fla. 'Tex. Colo. S.D.; Mex., C. Am., and W. 

 Ind. Plain Son. Mr-X. 



14. HOMALOCENCHRUS Mieg. RICE CUT-GRASS. 



Perennials. Panicles usually open, rarely contracted, terminal, the branches 

 slender. Spikelets often with a cartilaginous ring at the base, articulated below 

 the scales, compressed, 1-flowered. Glumes 2, compressed-keeled, somewhat 

 rigid, awnless, the first one usually ciliate on the keel, broader than the second, 

 which encloses a perfect flower but no palet. Stamens 1-6. Styles short or 

 slender, distinct; stigmas plumose with branched hairs. [Leersia Sw., not Hedw.] 



1. H. oryzoides (L.) Poll. Stem 3-15 dm. high, often rooting at the nodes; 

 leaf-blades 6-25 cm. long, 4-13 mm. wide, very rough; terminal panicle 1-2 dm. 



