FLORA OF THE DISTRICT OF COLUMBIA. 83 



21. PHLETTM L. 

 1. Phleum pratense L. Timothy. 



Meadows, pastures, and open ground. June-July. Cultivated as a meadow grass 

 and naturalized throughout the cooler and moist parts of the U. S.; native of Eur. 



22. ALOPECURUS L. 



Spike cylindrio; glumes distinctly ciliate on the keels 1. A. geniculatus. 



Spike tapering above and below; glumes scarcely ciliate on the keels. .2. A. agrestis;. 



1. Alopecurus geniculatus L. 



Banks of ditches and streams; rare. May-June. Widely distributed in the U. S.; 

 also in Eur. and Asia. (Including A . geniculatus aristulatus of Ward's Flora.) 



2. Alopecurus agrestis L. 



Old fields and waste places; rare. A European grass, occasionally found introduced 

 in waste places. 



23. SPOROBOLUS R. Br. Drop-seed grass. 



Plants perennial; palea acuminate, longer than the lemma 1. S. clandestinus. 



Plants annual; palea not longer than the lemma. 



Spikelets 4 mm. long; lemma pubescent 2. S. vaginae florus. 



Spikelets 2.5-3 mm. long; lemma glabrous 3. S. neglectus. 



1. Sporobolus clandestinus (Spreng.) Hitchc. 



Sandy soil; Great Falls to High Island; infrequent. Eastern U. S. (Vtifa aspera 

 of Ward's Flora.) 

 All our species of Sporobolus are fall-flowering. 



2. Sporobolus vaginaeflorus (Torr.) Wood. 



Waste ground or sandy soil; frequent. Eastern U. S. 



3. Sporobolus neglectus Nash. 



Waste ground or sandy soil; frequent. Northern states, south to Va. 



24. CINNA I,. 

 1. Cinna arundinacea L. Wood reed-grass. 



Moist woods; frequent. Aug.-Sept. Northern states, south to N. C. 



25. AGROSTIS L. Bent grass. 



Palea present. Panicle many-flowered, rather compact; plants usually tall. 

 Ligule of the culm leaves long, mostly 3-5 mm.; panicle large and many-flowered, 



usually closing after flowering; culms 50-100 cm. tall 1. A. palustris. 



Ligule short; panicle small, rather few-flowered, open and spreading, remaining 



open after flowering; culms usually less than 40 cm. tall 2. A. capillaris. 



Palea wanting. 



Panicle diffuse, the branches long and capillary, branching toward the end. 



3. A. hiemalis. 

 Panicle spreading but not diffuse, the branches branching below the middle. 



B 4. A. perennans. 



1. Agrostis palustris Huds. Redtop. 

 Meadows, pastures, and open ground. June-July. Cultivated throughout the 



northern states as a meadow and pasture grass, and commonly escaped into open 

 moist ground; native of Eur. (A. alba of Ward's Flora.) 



2. Agrostis capillaris L. Rhode Island bent. 

 Open grassland; frequent. Cultivated as a lawn grass and escaped in the north- 

 eastern states; native of Eur. (A. alba vulgaris Thurb.: A. vulgaris With.) 



