84 CONTRIBUTIONS FEOM THE NATIONAL HERBARIUM. 



3. Agrostis hiemalis (Walt.) B. S. P. 



Open, dry or moist ground. June-July. Common throughout the U. S. (A. 

 scabra Willd.) 



A low delicate grass, the mature, very diffuse panicle breaking away and rolling 

 before the wind as a tumbleweed. Sometimes called tickle-grasa. 



4. Agrostis perennans (Walt.) Tuckerm. 



Dry or moist woods; common. Aug.-Sept. Northern states, south to N. C. 

 The ordinary form is erect and rather stiff. A form found in moist shady places 

 has decumbent stems and delicate, divaricately branched panicles. 



26. CALAMAGROSTIS Adans. Reed-grass. 



Spikelets 3-3.5 mm. long; rudiment hairy throughout; panicle rather open. 



1. C. canadensis. 

 Spikelets 6-7 mm. long; rudiment hairy at the tip; panicle contracted. 



2. C. cinnoides. 



1. Calamagrostis canadensis (Michx.) Beauv. 



Swales and moist woods; rare; Bladensburg; southwest of Rockville, near Cabin 

 John road. June- July. Northern U. S., south to Md., and in the mountains to N. C. 



2. Calamagrostis cinnoides (Muhl.) Barton. 



Boggy woods, especially magnolia bogs below the fall line. Aug. Northern states, 

 south to Ga. (C. nuttalliana Steud.) 



27. NOTHOLCUS Nash. 



1. Notholcus lanatus (L.) Nash. Velvet grass. 



Meadows and waste places; infrequent. June. Naturalized from Eur. in the 

 eastern states and on the Pacific Slope. {Holcus lanatus L.) 



28. AIRA L. 

 1. Aira caryophyllea L. 



Dry open ground; infrequent. May. Northern states and Pacific Slope; natu- 

 ralized from Eur. 



29. DESCHAMPSIA Beauv. 



1. Descliampsia flexuosa (L.) Trin. 



Dry woods; infrequent. May- June. Northern states, south to N. C; also in 

 Eur. {Aira flexuosa L.) 



30. TRISETUM Pers. 



1. Trisetum pennsylvanicum (L.) B. S. P. 

 Bogs; rare. Eastern U. S. {T. jmlustre Torr.) 



31. SPHENOPHOLIS Scribn. 



Panicle narrow, densely flowered; glumes equal in length, about 2 mm. long, the 



second much broadened above, 1 mm. wide 1. S. objusata. 



Panicle lax, the branches more or less spreading; glumes unequal in length, the 

 second longer, widened above, 0.5-0.75 mm. wide. 

 Glumes subequal, the second broadly obovate, obtuse; florets obtuse, the second 



scabrous 2. S. nitida. 



Glumes unequal, the first shorter than the narrowly obovate second one; florets 

 mostly acute, glabrous 3. S. pallens. 



1. Sphenopholis obtusata (Michx.) Scribn. 



Pocky woods; rare; Great Falls, on the Virginia side; also collected by Ward and 

 by Seaman, the localities not recorded. Jiine. Conn, to Fla. and westward. 



