GRASS FAMILY 89 



Lemma and glumes more or less pubescent. 13. B. hordeaceus 



Second empty glume 3-nerved; first empty glume 1-nerved, except in B Porteri 



Awns shorter than the lemma; plants perennial with rootstocks, all native excent 



B. inermis. 

 Inflorescence more or less drooping. 



Awn 6-9 mm. long; empty glumes sparingly pubescent or glabrous. 



14. B. eximius. 

 Awn 2-5 mm. long. 



Empty glumes decidedly pubescent. 



First empty glume 3-nerved; inflorescence nanow. 



15. B. Porteri. 

 First empty glume 1-nerved; inflorescence open. 



Sheaths with a ring of dense hairs at the base of the blades. 



16. B. latiglumis. 

 Sheaths without a ring of hairs. 17. B. purgans. 



Empty glumes glabrous or merely scabrous on the nerves. 



Lemma evenly pubescent on the back; sheaths densely hairy. 



18. B. lanatipes. 

 Lemma ciliate on the margins, glabrous or sparingly hairy on the back; 



sheaths glabrous or the lower sparingly hirsute. 19. B. 'ciliatus. 

 Inflorescence not drooping. 



Inflorescence narrow; its branches erect; lemma usually with awn 2-3 mm. 

 long. 20. B. Pumpellianus. 



Inflorescence broad: its branches spreading; lemma usually awnless. 



21. B. inermis. 

 Awn longer than the lemma; introduced tufted annuals. 



Spikelets numerous on slender, recurved pedicels; lemma 8-12 mm. long. 



22. B. tectorum. 

 Spikelets few; pedicels not recurved; lemma 12-30 mm. long. 



Awn less than 3 cm. long. 23. B. sterilis. 



Awn 3.5-4 cm. long. 24. B. maximus. 



1. B. Hookerianus Thurb. Annual or biennial; stem erect, 4-8 dm. high; 

 leaf-blades flat, 1-2.5 dm. long, 5-12 mm. wide; panicle 2-4 dm. long; branches 

 spreading; spikelets 5-10-flowered, 3-4 cm. long, 5-7 mm. wide; empty glumes 

 glabrous, 15-18 mm. long, gradually acuminate; lemma about 2 cm. long, broadly 

 hyaline-margined. Plains: B.C. Ida. Calif. Submont. My-Jl. 



2. B. Flodmanii Rydb. Short-lived perennial; stem glabrous, 6-10 dm. 

 high; leaf-blades 2-3 dm. long, 6-10 mm. wide, minutely scabrous; panicle 

 1-2 dm. long; spikelets 2.5-3.5 cm. long, 5-7 mm. wide; empty glumes lanceolate, 

 about 1 cm. long, glabrous, acute; lemma about 15 mm. long, scabrous, narrow- 

 margined, acuminate. Meadows: Mont. Submont. 



3. B. breviaristatus (Hook.) Buckl. Tufted short-lived perennial; stem 

 6-12 dm. high; leaf-blades sparsely pilose throughout or glabrate, 1.5-2.5 dm. 

 long, 6-12 mm. wide; panicle erect, narrow, 1-2 dm. long; spikelets 2.5-4 cm.. 

 long, 5-7 mm. wide, 7-9-flowered; empty glumes scabrous or scabrous-puberu- 

 lent; lemma 11-14 mm. long; awn 4-5 mm. long. B. marginatus Nees. Mead- 

 ows: B.C. Calif. Colo. Neb. Alta. Submont. 



4. B. subvelutinus Shear. Erect tufted perennial; stem pubescent above, 

 2.5-5 dm. high; leaf-blades linear, rigid, involute, canescent, with spreading 

 hairs; panicle 5-10 cm. long, narrow, erect; spikelets short-pediceled or subses- 

 sile, 5-7-flowered, 2-3 cm. long; empty glumes puberulent, 8-12 mm. long; 

 lemma appressed-pubescent; awn 3-4 mm. long. Arid regions: Nev. Calif. 

 Wash. Ida. Son. 



5. B. latior (Shear) Rydb. Stout perennial; stem 7-18 dm. high; leaf-blades 

 2-3 dm. long, 7-10 mm. wide, more or less pilose; panicle 2-3 dm. long; spike- 

 lets 2.5-4 cm. long, 6-8 mm. wide; empty glumes pubescent, about 1 cm. long, 

 acuminate; lemma densely pubescent, about 15 mm. long, acuminate, slightly 

 bifid; awn 6-7 mm. long. B. marginatus latior Shear. Meadows: Wash. 

 Calif. N.M. Mont. Submont. Mont. Je-Au. 



6. B. polyanthus Scribn. Stout short-lived perennial; stem glabrous, or 

 puberulent at the nodes; leaf-blades 1-2 dm. long, 4-8 mm. wide, scabrous, 

 especially above; panicle 1-2 dm. long; spikelets 3-3.5 cm. long, densely 7-11- 

 flowered: empty glumes smooth or nearly so, subacute or obtuse; lemma smooth 

 or minutely scabrous. Meadows: Mont. N.M. Utah Ore. Submont. 

 Subalp. Je-Au. 



