GRASS FAMILY. 



31 



like; when the spikelets are crowded in pairs on one side of flattened 

 spikelike branches, one spikelet is sessile the other pedicellate. 

 Spikelets without involucre or bristles at the base, 1 or 2-flowered 

 (when 2-flowered the lowest staminate) rarely awned, jointed on the 

 pedicels below the bracts so that these fall away with the flower at 

 maturity; bracts 2 (or 1 only); the lower smaller, often minute or 

 obsolete; the upper equaling the perfect flower. Bractlets 2; the upper 

 enclosing the palea and a perfect flower; the lowerresembling the upper 

 bract and empty or bearing a staminate flower or empty palea, the 

 latter when present very thin and hyaline; upper bractlet and its 

 palea alike, coriaceous or cartilaginous, usually flattened parallel with 

 the bracts, awnless. Scales 2, fleshy, truncate. Ovary smooth, 

 oblong; styles distinct or very shortly united at the base; stigmas 

 usually purple and longer than the styles. Achene compressed, 

 plano-convex, enclosed by the indurated bractlet and palea. (The 

 Latin name for some cereal, from panis, bread, one species — the 

 Millet, P. miliaceum — having been cultivated from prehistoric times 

 as a cereal.) 



Spikelets crowded in 2 to 4 rows on 2 sides of triangular, digitate or clustered 

 spikes. 



Lower bract minute or obsolete; bractlets awnless, pubescent or nearly 



smooth I. P. sanguinale. 



Spikelets imbricate, sessile on 2 sides of a triangular rachis, usually rough with 

 stiff hairs. 



Bractlet awned or awn-pointed, mostly shortly hirsute on the nerves .... 



2. P. Crus-galli. 



Spikelets in lax panicles, pedicellate, awnless. 

 Annual; spikelets acutely pointed; panicle-branches mostly angular .... 



3. P. capillare. 



Perennial; spikelets obtuse or barely pointed; panicle-branches filamentous. 



4. P. dichotomum. 



1. P. sanguinale L. Crab-grass. Glaucous annual; stems usu- 

 ally prostrate and creeping at base, then ascending or erect, 1 to 2 ft. 

 long, usually stout; lower nodes swollen and rooting; sheaths spar- 

 ingly hairy with long, stiff, white hairs; throat with a tuft of hairs 

 on each side; ligule about 1 line long, broad, truncate, denticulate; 

 blades 2 to 4 in. long, 2 to 3 lines wide, scabrous on both sides; 

 panicle-branches, 4 to 6 or more, digitate or clustered, sub-erect, 

 straight, 3 to 5 in. long, 3-sided, spikelet-bearing to the base on 2 

 sides only, about £ line wide on the broad side, ciliate-scabrous; spike- 

 lets in pairs, in 2 to 4 rows, narrowly lanceolate-acuminate, 1^ to 1£ 

 lines long, one on a ciliate-scabrous triangular pedicel, the other 

 sessile below it and overlapping; bracts much shorter than the spike- 

 let; lower less than £ line long, triangular, acute; upper f to 1 line 

 long, linear, 3 to 5-nerved, ciliate with long hairs; lower bractlet 

 empty, membranous, 3 to 5 or 7-nerved, ciliate; upper rather shorter, 

 faintly 3-nerved, chartaceous, glabrous, completely enclosing the 

 palea; achene flattened, oblong, 1 line long. 



A cosmopolitan weed. Elk Grove, Drew; Lower Sacramento, 

 Jepson; Stege; Napa Co. July-Sept. 



2. P. Crus-galli L. Barn yard-grass. Annual; stems ascend- 



