26 POACEAE. 



Second glume not toothed or slightly so; flowering glume awnless or rarely 



very short-awned. 



Empty glumes more than half as long as the flowering glume, acuminate. 

 Flowering glumes scabrous, green or dark. 



Panicle dense, obtuse, 5-10 mm. wide. 4. M. Wrightii. 



Panicle slender and lax, attenuate at the apex, less than 5 mm. wide. 



5. M. cuspidata. 

 Flowering glumes more or less purplish, sparingly long-hairy. 



6. M. Thurberi. 

 Empty glumes less than half as long as the flowering glume, obtuse or 



abruptly acute. 

 Spikelets (excluding the awn if present) 1.5 mm. or more long. 



Plant with a strong perennial, scaly root-stock. 7. M. Richardsonis. 

 Plant annual ; root-stock, if any, very slender. 



Flowering glumes merely awn-pointed, decidedly purplish ; plant 1-2 



dm. high. 

 Spikelets 2 mm. long or more ; inflorescence short and rather 



dense ; stem 0.5-1 mm. thick. 8. M. simplex. 



Spikelets about 1.5 mm. long; inflorescence slender and lax; 



stem very slender, filiform. 9. M. filiformis. 



Flowering glumes with a distinct awn J^-i mm. long, greenish ; 



plant 4-6 cm. high. 10. M. aristata. 



Spikelets about i mm. long ; plant less than 4 cm. high, annual. 



n. M. Wom. 

 Second glume sharply 3-s-toothed; flowering glume long-awned ; awn at 



least Yz as long as the glume. 

 Stem 3-6 dm. high, leafy; panicle 7-12 cm. long; awn 8-15 mm. long. 



12. M. gracilis. 

 Stem 1-3 high, almost naked above ; panicle 5-7 cm. long ; awn 1-4 mm. 



long. 

 Spikelets 3-4 mm. long ; awn 2-4 mm. ; leaves usually stiff. 



13. M. subalpina. 

 Spikelets about 2 mm. long; awn 1-2 mm.; leaves filiform. 



14. M. filiculmis. 

 Panicle open, its branches long and spreading. 



Plants densely cespitose, branched only at the base. 



Secondary branches of the panicle single; basal leaves short, strongly re- 

 curved. 15. M. gracillima. 

 Secondary branches of the panicle fascicled; basal leaves not recurved. 



1 6. M. pungens. 

 Plants diffusely branched, prostrate. 17. M. Porteri. 



1. Muhlenbergia mexicana (L.) Trin. In wet meadows and swamps from 

 N. B. to N. D., N. C. and Colo. Alt. 4000-6500 ft. New Windsor, Weld 

 Co.; Rocky Ford; Fort Collins; gulch west of Soldier Canon; Tobe Mil- 

 ler's ranch, near La Porte. 



2. Muhlenbergia racemosa (Michx.) B. S. P. (M. glomerata Trin.) In 

 wet meadows from Newf. to B. C., N. J., N. M. and Ore. Alt. 4000-10,000 

 ft. Colorado Springs; Cheyenne Mountain; Engelmann Canon; vicinity of 

 Ouray; New Windsor, Weld Co.; Estes Park, Larimer Co.; Fort Collins; 

 Black Canon; Deer Run; Manitou; Middle Park. 



3. Muhlenbergia comata (Thurb.) Benth. In wet soil, especially in sand 

 from Mont, to Wash., Kans. and Calif. Alt. 6500-10,000 ft. Mountains near 

 Pagosa Peak; Gunnison; Carlton Lake, Grand Co.; Georgetown; Gypsum 

 Creek Canon, Eagle Co. ; Twin Lakes ; Hinsdale Co. ; Empire. 



4. Muhlenbergia Wrightii Vasey. In wet places in the mountains of Colo., 



