92 



POACEAE 



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



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



1. L. perenne L. Stem 2-8 dm. high, smooth; leaf-blades 5-12 cm. longi 

 2-4 mm. wide, smooth; spike 7-20 cm. long; spikelets 5-10-flowered, 8-12 mm- 

 long; empty glume strongly nerved; lemma 4-6 mm. long, acuminate, awnless. 

 Waste places and cultivated ground: N.S. — Va. — N.M. — -Calif. — B.C. nat. 

 from Eurasia, Je-Au. 



2. L. temulentum L. Stem 6-12 dm. high, smooth; leaf-blades 1-2.5 dm. 

 long, 2-6 mm. wide, smooth beneath, rough above; spike 1-3 dm. long; spikelets 

 4-8-flowered, 10-18 mm. long; empty glume strongly veined; lemma awned or 

 awnless. Poisonous. Waste places and cultivated ground: N,B. — Ga. — Calif. 

 ^-B.C; nat. from Eu. Je-Au. 



72. AGROPYRON Gaertncr. Wheat-grass, Quitch-grass, 



Quick-grass. 



Perennials with terminal, 2-sided spikes; spikelets compressed, with the side 

 of the spikelet towards the rachis, usually single at each node; flowers perfect, 

 or the upper ones imperfect; rachilla articulate between the flowers. Empty 

 glumes 2, standing at right angles to the median plane of the spike, i. e., with 

 one edge toward the rachis, usually firm. Lemma broader, rigid, rounded on 

 the back, from obtuse to acuminate, awnless or awned. Palct shorter than the 

 lemma, 2-keeled, ciliate on the keels. Styles very short; stign:ias plumose. 

 Fruit enclosed in the lemma, adherent to the palet. 



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



lerama long-awned. 1. A. Scribneri. 



Rachis 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 compressed. 



Spikelets erect, empty glumes nearly equalling the spikelet. 



3. A. VaJ^eyi. 

 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 awn-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. thick, erect, but usually unilateral; 



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



7. A. Richardsonu 



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. 

 Lerama densely pubescent; empty glumes conspicuously white-margined. 



10. A. latiglume. 

 Lemma glabrous or scabrous; empty glumes not conspicuously wliite- 

 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. tcncrum. 

 Spikelets flattened; empty glumes much shorter than the spikelets. 



13. A. inermc, 

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



vations extravaginal. 

 Lemma with a long, more or less divergent awn. 



Lemma pubescent. 14. A. albicans. 



Lemma glabrous or scabrous. 



Spikelets subterete. appressed. 15. A. Griffithsii. 



