MANUAL OF THE GRASSES OF THE UNITED STATES 313 



TRIBE 5. AGROSTIDEAE 

 67. CALAMAGROSTIS Adans. Reedgrass 



Spikelets 1-flowered, the rachilla disarticulating above the glumes, pro- 

 longed behind the palea (in our species, except Calamagrostis epigeios) as a 

 short, commonly hairy bristle; glumes about equal, acute or acuminate; 

 lemma shorter and usually more delicate than the glumes, usually 5-nerved, 

 the midnerve exserted as an awn, the callus bearing a tuft of hairs, these often 

 copious and as long as the lemma. Perennial, usually moderately tall grasses, 

 mostly with creeping rhizomes, with small spikelets in open or usually narrow, 

 sometimes spikelike, panicles. Type species, Arundo calamagrostis L. Name 

 from Greek kalamos, a reed, and agrostis, a kind of grass, the type species being 

 a reedy grass. American species belong to the Section Deyeuxia, in which the 

 rachilla is prolonged. In Section Epigeios, of the Old World (one species intro- 

 duced), the rachilla is not prolonged. 



Several species are important native forage grasses. Pinegrass, C. rubescens, 

 is a leading range grass in the mountains of Oregon and Washington. Blue- 

 joint, C. canadensis, is a source of much of the wild hay of Wisconsin and 

 Minnesota. On the plains and bench lands of Wyoming and northward, C. 

 montanensis furnishes forage, especially when young. In low wet lands of the 

 Northern States C. inexpansa is grazed especially by horses and cattle. 



la. Awn longer than the glumes, geniculate. 

 2a. Panicle open, the branches spreading, naked below. 



Blades scattered, 5 to 9 mm. broad, flat; plant mostly more than 1 m. tall. 



1. C. BOLANDERI. 



Blades mostly basal, mostly not more than 2 mm. wide, often involute. 



Awn about 1 cm. long, much longer than the glumes; blades nearly or quite as long 



as the flowering culms 2. C. howellii. 



Awn only a little exceeding the glumes; blades much shorter than the culms, capillary, 



sulcate, folded 3. C. breweri. 



2b. Panicle compact, the branches appressed, floriferous from base. 



Blades scattered, broad and flat, 6 to 10 mm. wide 4. C. tweedyi. 



Blades mostly basal, firm, narrow, becoming involute. 



Glumes about 1 cm. long, gradually long-acuminate; awn nearly 1 cm. long above 



the bend , 5. C. foliosa. 



Glumes 6 to 8 mm. long, abruptly acute or acuminate; awn usually less than 5 mm. 



long above the bend 6. C. purpurascens. 



lb. Awn included or scarcely longer than the glumes, straight or geniculate. 

 3a. Awn geniculate, protruding sidewise from the glumes; callus hairs rather sparse, 

 shorter than the lemma. 

 Plants tufted, not rhizomatous, less than 40 cm. tall; blades 1 to 2 mm. wide, soon in- 

 volute, at least toward the tip. 



Panicles compact, spikelike; northwestern 7. C. montanensis. 



Panicles loose, open, relatively few-flowered; Tennessee 8. C. cainii. 



Plants rhizomatous, mostly more than 60 cm. tall; blades mostly more than 4 mm. 

 wide, flat. 

 Sheaths, or some of them, pubescent on the collar. 



Callus hairs one-third as long as lemma; western species 9. C. rubescens. 



Callus hairs half to three-fourths as long as lemma; eastern species. 



Palea about as long as the lemma 10. C. porteri. 



Palea three-fourths as long as the lemma 11. C. perplexa. 



Sheaths glabrous on the collar. 



Culms stout, mostly more than 1 m. tall. 



Panicles loose, the branches ascending or spreading 17. C. nutkaensis. 



Panicles compact 18. C. densa. 



Culms slender, mostly less than 1 m. tall. 



Hairs on callus and rachilla scant, less than 1 mm. long. 



Spikelets 5 mm. long; panicle spikelike 19. C. koelerioides. 



Spikelets 4 mm. long; panicles scarcely spikelike, some of the branches naked 



below 16. C. pickeringii. 



Hairs on callus and rachilla rather prominent, at least half as long as the lemma. 



