26 POACEAE 



Lemma long-hairy towards the apex. 

 Lemma about 5 ram. long. 



Glumes green, rarely slightly tinged with purple; lemma nearly glab- 

 rous below. 8. S. Lellermanii. 

 Glumes purplish with paler margins; lemma pubescent throughout, 

 though more densely so above. 9. S. pinelorum. 

 Lemma about 8 mm. long. 10. S. Scribneri. 

 Lemma equally hairy throughout. 

 Sheaths glabrous. 



Empty glumes scarious or hyaline; their nerves hence promment. 



Lemma 4-6 mm. long, spindle-shaped when mature; callas short. 

 Stem-leaves broader than the basal leaves, often flat; sheaths 



with a ring of hairs at the throat. 11. S. viriduln. 



Stem-leaves as well as the basal leaves very narrow, involute; 

 sheaths glabrous. 

 Plant green; sheaths close; inflorescence distinctly exserted. 



12. S. Columbiana. 

 Plant pale and glaucous; sheaths loose; inflorescence inchided 

 or barely exserted; awn glabrous. 13. S. arida. 

 Lemma 6-7 mm. long, almost cylindric; callus long and pointed. 



14. S. Nelsonii. 

 Empty glumes Arm, thicldsh, herbaceous; the nerves not prominent. 



Lemma about 5 mm. long; leaf-blades narrow and involute. 



15. S. minor. 

 Lemma 8-10 mm. long; leaf-blades broad. 



Panicle slender; stem low and slender. 9. 5. Scribneri. 



Paniclestoutandden.se; stem tall and stout. 16. ,5. Vaseyi. 

 Sheaths and lower leaf-blade pubescent. 17. S. Williamsii. 



Awns plumose or subplumose at least below. 



Hairs of the awns less than 1 mm. long; empty glumes 10-12 mm. long. 

 Ligules 1 nun. long or less. 



Sheaths, at least the lower ones, hairy. 18. S. Elmeri. 



Sheaths glabrous. 19. S. oregonensis. 



Ligules 2-4 mm. long. 20. S. Thurberiana. 



Hairs of the awns 3-6 mm. long; empty glumes 15-18 mm. long. 



21. S. speciosa. 



19. ORYZOPSIS Miohx. Mountain Rice. 



Lenmia glabrous, or pubescent with short appressed hairs. 



Spikelets, exclusive of the awn, 2.5-5 mm. long; leaves slender and involute. 



Awn less than 2 mm. long, much shorter than the glume; outer glumes 3-4 mm. 



long. 1. O. pungens. 



Awn 4—8 mm. long, much longer than the glume. 



Inflorescence very narrow, with short erect branches; outer glumes 3-5 mm. 



long. 2. O. exigua. 



Inflorescence at length open, with long spreading or reflexed branches; outer 

 glume about 2.5 mm. long. 3. O. micraniha. 



Spikelets, exclusive of the awn, 6-8 mm. long; leaves broad and usually flat. 



4. O. asperifolia. 

 Lemma with long loose hairs. 



Inflorescence open; plant 3-6 dm. high. 5. O. Bloomeri. 



Inflorescence narrow and spike-like; plant 1-3 dm. high. 6. O. Webberi. 



20. ERIOCOMA Nutt. Indian Millet, Wild Rice. l. E. hymenoides. 



21. MUHLENBERGIA Schreb. 



Panicle contracted, narrow, spike-like, the short branches rarely spreading. 



Empty glumes awl-shaped; leafy and branched plants, with long rootstocks covered 

 by imbricated scales. 

 Lemma not awned; basal hairs not equalling the lemma. 



Empty glumes about equalling the lemma in length, sharp-pointed, about 3 



mm. long. 1. M. mexicana. 



Empty glumes exceeding the lemma, generally twice as long, awned, about 

 5 mm. long. 2. M. racemosa. 



Lemma distinctly awned; basal hairs equalling the lemma. 3. M. comata. 

 Empty glumes lanceolate to ovate. 



Second glume not toothed or slightly so. 



Lemma awnless oi rarely very short-awned. 



Empty glumes more than half as long as the lemma. 



Plant 1.5—7 dm. high; sheaths close; empty glumes acuminate, lanceolate. 

 Lemma 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. 



Lemma more or less purpUsh, sparingly long-hairy. 



6. M. Thurberi. 

 Plant less than 1.2 dm. high; sheaths loose; lower leaves lanceolate, 

 short, squarrose; empty glumes ovate, acute. 7. M. squarrosa. 

 Empty glumes less than half as long as the lemma, obtuse or abruptly 

 acute. 

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

 Plant with a strong perennial, scaly rootstock. 



