GENUS 72. 



GRASS FAMILY. 



2 33 



i. Sieglingia decumbens (L.) Kuntze. Heath- or Heather-grass. Fig. 560. 



Festuca decumbens L. Sp. PI. 75- 1753- 

 Triodia decumbens Beauv. Agrost. 76. 1812. 

 S. decnmbens Bernh. Syst. Verg. Erf. i : 20, 44. 



1800. 



Culms 6'-i8' tall, erect, often decumbent at the 

 base, simple, smooth and glabrous. Sheaths shorter 

 than the internodes, villous at the summit; ligule a 

 ring of very short hairs; blades smooth beneath, 

 usually scabrous above, $"-ii" wide, the basal 3'-6' 

 long, those of the culm i'~3' long; panicle i'-2 f long, 

 contracted, the branches i' long or less, erect; spike- 

 lets 3-5-flo\vered, 3"-5" long, the joints of the rachilla 

 very short; lower scales equalling the spikelet, acute; 

 flowering scales broadly oval, ciliate on the margins 

 below, obtusely 3-toothed, with two tufts of hair on 

 the callus. 



Introduced into Newfoundland. Native of Europe and 

 Asia. Moor-grass. Summer. 



73. TRIDENS R. & S. Syst. 2 : 34. 1817. 

 [TRICUSPIS Beauv. Agrost. 77. 1812. Not Pers. 1807.] 



Usually perennial grasses, with flat or involute leaf-blades, and the inflorescence com- 

 posed of open or contracted and sometimes spike-like panicles. Spikelets 3-many-flowered, 

 the flowers perfect or the upper ones staminate. Scales s-many, membranous, sometimes 

 firmer, the 2 lower empty, keeled, obtuse to acuminate, usually snorter than the rest, some- 

 times longer ; flowering scales 3-nerved, the midnerve or all the nerves excurrent, the mid- 

 nerve and the lateral nerves or the margins pilose, the apex entire or shortly 2-toothed, the 

 teeth obtuse to acute, the callus short and obtuse; palet shorter than the scale, compressed, 

 2-keeled. Stamens 3. Styles short, distinct. Stigmas plumose. [Latin, in reference to the 

 teeth of the flowering scales.] 



Species about 30, natives chiefly of temperate regions. Type species : Poa coerulescens Michx. 



i. T.flava. 



Panicle open, the branches spreading and often drooping. 

 Panicle contracted, spike-like. 



Second empty scale i -nerved; flowering scales about 2" long. 



Second empty scale 3-s-nerved ; flowering scales 2 l / 2 "-3" long. 



2. T. stricta. 



3. T. elongate. 



i. Tridens flava (L.) Hitchc. Tall Red-top. Fig. 561. 



Poa flava L. Sp. PI. 68. 1753. 



Poa seslerioides Michx. Fl. Bor. Am. i : 68. 1803. 

 Tricuspis seslerioides Torr. Fl. N. Y. 2 : 463. 1843. 

 Sieglingia seslerioides Scribn. Mem. Torr. Club 5: 48. 1894. 

 Tridens flava Hitchc. Rhodora, 8: 210. 1906. 



Culms 2-s tall, erect, often viscid above. Sheaths 

 sometimes villous at the summit, equalling or shorter than 

 the internodes; ligule a ring of very short hairs; blades 

 4'-! long or more, 3"-6" wide, flat, attenuate into a long 

 tip, smooth beneath, scabrous above; panicle 6'-i8' long, 

 the branches finally ascending or spreading, the lower 

 4'-io' long, usually dividing above the middle; spikelets 

 4-8-flowered, 3"-4" long, purple; joints of the rachilla 

 short; empty scales glabrous, obtuse, generally slightly 

 2-toothed ; flowering scales oval, the nerves pilose, ex- 

 current as short points. 



In fields. Massachusetts and New York to Kansas, south to 

 Florida and Texas. July-Sept. 



