FLORA OF THE DISTRICT OF COLUMBIA. 87 



6. Eragrostis pilosa (L.) Beauv. 



Moist places; infrequent. Eastern states; introduced from Eur, 



7. Eragrostis caroliniana (Spreng.) Scribn. 



A common weed in open moist ground. Throughout the eastern and southern 

 U. S. (E. purshii Schrad.) 



8. Eragrostis minor Host. 



Open waste ground; rare; Beltsville; Anacostia. Late summer. Occasional at 

 scattered localities throughout the U. S.; introduced from Eur. (E. eragrostis Karst.) 



43. MELICA L. 

 1. Melica mutica Walt. 



Rocky woods; frequent above the fall line. Southern states, north to Pa. 



44. UNIOLA L. 



Panicle contracted, slender; spikelets 5-7 mm. long, narrow 1. XJ. laxa. 



Panicle open, the branches drooping; spikelets 1.5-3 cm. long, broad and very flat. 



2. IT. latifolia. 



1. TJniola laxa (L.) B. S. P. 



Moist woods; east of the fall line; infrequent. Summer. Southern states, north- 

 ward to Long Isl. ( XI. gracilis Michx.) 



2. TJniola latifolia Michx. 



Rich woods; above the fall line. Summer. Southern states, north to Pa. 



A handsome grass, the drooping panicles of large, very flat spikelets being very 

 striking. 



• 45. DACTYLIS L. 

 1. Dactylis glomerata L. Orchard grass. 



Cultivated as a meadow grass; frequently established in grassland and along road- 

 sides. May. Native of Eur. 



46. POA L. Bluegrass. 

 Plants annual. 



Florets not cottony at base; intermediate nerves of lemma distinct 1. P. annua. 



Florets with cottony hairs at base ; intermediate nerves indistinct. 2. P. chapmaniana . 

 Plants perennial. 



Creepingjrootstocks present. 

 Culms distinctly flattened; plants not tufted; panicles contracted. 



3. P. compressa. 

 Culms terete or obscurely flattened; plants tufted; panicles open. 

 Lower branches of the panicle usually in twos; basal leaves usually as long as 



the culm 4. P. cuspidata. 



Lower branches of the panicle usually in fives; basal leaves shorter than the 



culm 6. P. pratensis. 



Creeping rootstocks wanting. 



Lemma not cobwebby at base, conspicuously scarious at the rounded apex. 



6. P. autumnalis. 

 Lemma cobwebby at base. 

 Sheaths upwardly scabrous; marginal nerves of the lemma glabrous. 



7. P. trivialis. 

 Sheaths glabrous; marginal nerves of the lemma pubescent. 

 Intermediate nerves of the lemma faint; branches of the panicle ascending 



or spreading; lemma usually purple-tinged 8. P. palustris. 



Intermediate nerves of the lemma prominent; branches of the panicle finally 

 reflexed; lemma green 9. P. sylvestrls. 



