32 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



Section 1. Ceratochloa 



Lemmas awnless or nearly so 1. B. catharticus. 



Lemmas awned, the awn more than 3 mm. long. 



Panicle branches elongate, slender, drooping, bearing 1 or 2 large spikelets at the end, the 

 lowermost naked for as much as 10 to 15 cm. Sheaths smooth; Washington and 



Oregon 2. B. sitchensis. 



Panicle branches not greatly elongate. 



Panicle branches ascending, rather stiff, naked below, bearing 1 or 2 large spikelets. 



Washington 3. B. aleutensis. 



Panicle branches short and ascending or longer and drooping, with some short branches 

 at the base. 

 Blades canescent, densely short-pilose, 2 to 5 mm. wide, often involute; panicle 



narrow 4. B. breviaristatus. 



Blades not canescent, glabrous to puberulent or sparsely pilose, mostly 5 to 12 mm. 

 wide. 

 Sheaths strongly to sparsely retrorsely pilose; blades 4 to 12 mm. wide; lemmas 

 usually pubescent, the awns mostly less than 7 mm. long; plants perennial. 



7. B. MARGINATUS. 



Sheaths scaberulous to pilose. 



Plants annual or biennial; culms mostly 30 to 100 cm. tall; spikelets rather open 

 at anthesis, the rachilla joints relatively long; awns 7 to 15 mm. long. 

 Spikelets 6- to 10-flowered; second glume shorter than the lowest lemma. 



5. B. CARINATUS. 



Spikelets mostly 5- to 7- flowered; second glume nearly or quite equaling the 



length of the lowest floret 6. B. arizoxicus. 



Plants perennial; awns mostly less than 15 mm. long. 



Culms erect, mostly 80 to 120 cm. tall; panicle mostly open; spikelets rather 



glossy, loose, the rachilla joints relatively long 9. B. polyanthus. 



Culms subgeniculate and leafy at base, mostly 25 to 70 cm. tall; panicle rather 

 dense; spikelets closely flowered 8. B. maritimus. 



Section 2. Bromopsis 



la. Creeping rhizomes present; lemmas awnless or short-awned; panicle erect, somewhat 

 open, the branches ascending. 



Lemmas glabrous 10. B. inermis. 



Lemmas pubescent near the margins 11. B. pumpellianus. 



lb. Creeping rhizomes wanting (base of culm decumbent in B. laevipes). 

 2a. Panicle narrow, the branches erect. 



Lemmas glabrous or evenly scabrous 12. B. erectus. 



Lemmas appressed-pubescent on the margins and lower part 13. B. suksdorfii. 



2b. Panicle open, the branches spreading or drooping. 

 3a. Lemmas glabrous. 

 Blades broad and lax, more than 5 mm., at least some of them 10 mm., wide (var. 



laeviglumis) 20. B. purgans. 



Blades narrow, not more than 6 mm. wide 23. B. texensis. 



3b. Lemmas pubescent. 



4a. Lemmas pubescent along the margin and on lower part of the back, the upper 

 part glabrous. 

 First glume 3-nerved; plant mostly pale or glaucous. Culms decumbent at base. 



17. B. laevipes. 

 First glume 1-nerved, or only faintly 3-nerved near the base; plants dark green. 

 Ligule prominent, 3 to 5 mm. long; lemmas narrow; awn usually more than 5 mm. 



long 18. B. VULGARIS. 



Ligule inconspicuous, about 1 mm. long; lemmas broad; awn 3 to 5 mm. long. 



19. B. CILIATUS. 

 4b. Lemmas pubescent rather evenly over the back, usually more densely so along 

 the lower part of the margin (glabrous in B. purgans var. laeviglumis). 

 Panicle branches short, stiffly spreading; blades short, mostly on lower part of 



culm 14. B. ORCUTTIANUS. 



Panicle branches lax or drooping; blades along the culm, mostly elongate. 



Panicle small, drooping, usually not more than 10 cm. long. Spikelets densely 

 and conspicuously pubescent. 

 Sheaths and blades sparsely pilose to subglabrous; blades mostly 2 to 4 mm. 



wide (rarely 5 to 6 mm.) 24. B. anomalus. 



Sheaths and blades (except uppermost in some) conspicuously pubescent; 

 blades 5 to 10 mm. wide 25. B. kalmii. 



