1. Bromus L. Bromegrass. 
Annuals or perennials with narrow or open panicles of large spikelets. 
Spikelets several flowered, the rachilla disarticulating above the glumes 
and between the florets; glumes acute or acuminate, unequal, the first 
1-3 nerved, the second 3-5 nerved; lemmas keeled or rounded on the back, 
awnless or usually awned from between the teeth of the bifid apex. 
O Spikelets distinctly flattendd; glumes and lemmas keeled 
2 Sheaths and lemmas glabrous 1. Be polyanthus 
2 Sheaths and lemmas pubescent 
Sheaths densely soft-pubescent; blades erect, 
® pubescent like the sheaths, 2-5 mn. wide 4. Be 
Sheaths pubescent but not velvety; blades spreading, 
~ / scabrous, at least sone of them more than 5 mn. 
(wide 
G Avwns less than 7 mn. usually about 5 mm. long 2 Be marginatus 
( Awns more than 7 mm. long de Be carinatus 
Oo Spikelets not flattened; glumes and lemmas rounded on the 
4 back, or keeled only toward the summit 
te SA be aks «ea Some et alll acs 
2 Plants perennial; native species (except B. inermis) 
apa 
4 Rhizomes present; lemmas awnless or short-awned o« Be inermis 
et 
4 Rhizomes wanting; lemmas long-awned : 
6 Ligule prominent, 2-3 mme long; awns more than 
10 5 mme long 6. Be vulgaris 
(> Ligule short; awns less than 5 mm. long 7. Be. ciliatus 
@ Plants annual; introduced species 
4 Lemmas narrow; second glume 1 om. or more long 
G@ Panicle branches slender and flexuous; awns 1-1.5 
/ocme long 8. Be. tectorum 
(> Panicle branches relatively stout, not flexuous; 
/Q awns 5-4 cm. long 9. Be rigidus 
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4 lLemneas broad; second Zlune no 
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Lemnas avniless 10. 38. brizaeformis 
maple 
& Panicles contracted, dense ll. B. bordeacous- 
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» Lemmas ayned 
