GRASS FAMILY 37 



Awn fuUv as long as the lemma, at maturity strongly divergent; sheaths 

 pubescent. 12. B. palulus. 



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 except 

 B. inermis. 

 Inflorescence more or less drooping. 



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



11. B. eximius. 

 Awn 2-5 mm. long. 



Empty glumes decidedly pubescent. 



First empty glume :i-nerved: inflorescence nan ow. 15. B. Porleri. 

 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: 

 sheatlis 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. teclorum. 

 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. 



71. LOLIUM L. Darxei., Rye-gr.\ss. 



Empty glumes shorter than the spikelet: perennial. 1. L. perenne. 



Empty glume longer than the spikelet; annual. 2. L. temulentum. 



72. AGROPYRON Gaertner. Wheat-grass, Quitch-grass, Quick-grass. 

 Uachis of the spike breaking up at maturity, the internodes falling with the spikelets; 



lemma long-awned. 1. A. Scribneri. 



Kachis of the spike remaining continuous. 



Tufted plants with intra vaginal innovations; no horizontal stolons (except in A. 

 arizonicum). 

 Lemma long-awned, i. e., the awn usually longer than the body of the lemma. 

 Basal leaf-blades shorter than the upper ones; spikelets slightly compressed; 



awns somewhat spreading. 2. A. Gmelini. 



Basal leaf-blades longer than the upper ones. 

 Awn divergent. 



Spikelets remote on the axis, more or less compres.sed. 



Spikelets erect, empty glumes nearly equalling the spikelet. 



3. .4. Vaseyi. 

 Spikelets spreading or ascending: empty glumes half as long as the 

 spikelet. 

 Empty glumes linear-oblong, acute or obtuse; stem-leaves 3 or 



4, not glaucous. 4. A. spicatum. 



Empty glumes narrowly lanceolate, acuminate or awm-pointed ; 

 stem-leaves 6 or 7, glaucous. 5. A. arizonicum. 



Spikelets crowded on the axis, subterete. 6. A. Bakeri. 



Awns erect. 



Plant tall, usually more than 3 dm. high, erect or ascending; empty 

 glumes broadest below the middle; spike elongated. 

 Stem stout; spike 7-10 mm. tliick, erect, but usually unilateral; 

 spikelets (exclusive of the awns) 15-25 mm. long. 



7. A. Richardsoni. 

 Stem slender; spike about 5 mm. thick, seldom unilateral; spikelets 

 (exclusive of the awns) about 1 cm. long. 8. A. caninoides. 

 Plant 2-3 dm. high, decumbent at the base, geniculate; empty glumes 

 broadest above the middle, scarious-margined ; spike short and 

 dense. 9. A. andinum. 



Lemma short-awned or awnless. 



Spikes stout and dense, 3-8 cm. long; empty glumes broadest above the middle. 

 Lemma densely pubescent; empty glumes conspicuously white-margined. 

 , 10. A. latiglume. 



Lemma glabrous or scabrous; empty glumes not conspicuously white- 

 margined. 11. A. biflorum. 

 Spike slender and lax, 7-20 cm. long; empty glumes broadest below the middle. 

 Spikelets terete, appressed; empty glumes nearly as long as the spikelets. 



12. A. tenerum. 

 Spikelets flattened; empty glumes much shorter than the spikelets. 



13. A. inermc. 

 Stoloniferous plants with horizontal rootstocks, sometimes slightly tufted; innova- 



vations extravaginal. 



