GRAMJNEAE. 153 



98. AGROP^RON J. Gaertn. 



Annual or perennial grasses, with flat or involute leaves and terminal spikes. 

 Spikelets 3-many- flowered, sessile, single and alternate at each notch of the usually 

 continuous rachis, the side of the spikelet turned toward the rachis. Two lower 

 scales empty; flowering scales rigid, rounded on the back, fj-y-nerved, usually 

 acute or awned at the apex; palets 2-keeled, the keels often ciliate. Stamens 3. 

 Styles very short, distinct. Stigmas plumose. Grain pubescent at the apex, 

 usually adherent to the palet. [Greek, referring to the growth of these grasses in 

 wheat- fields.] About 40 species, in all temperate regions. Besides the follow- 

 ing, some twelve others occur in the western parts of N. Am. 



Culms tufted, no creeping rootstocks or stolons. 



Basal culm-leaves longer than the upper ; empty scales awnless. 

 Flowering scales long-awned. 



Culms stout, erect ; spikes erect, often one-sided. i. A. Richardsonii. 



Culms geniculate, ascending; spikes nodding. 2. A. caninum. 



Flowering scales with a short awn or awnless. 



Spikes slender, 5-12 cm. long; empty and flowering scales broadest below 



the middle. 3. A. tenerum. 



Spikes 2.5-7 cm - l n g> empty and flowering scales broadest above the mid- 

 dle. 4. A. violaceum. 

 Basal culm-leaves shorter than the upper; empty scales short-awned 



5. A. Gmelini* 

 Culms from creeping rootstocks. 



Rachis articulated, finally breaking up; spikes 4-angled. 6. A. tetrastachys. 



Rachis continuous; spikes more or less flattened. 



Spikelets compressed, lanceolate to ovate, ascending. 7. A. spicatum. 



Spikelets nearly round or but little compressed, linear, erect. 



Flowering scales densely pubescent. 8. A. dasystachyum. 



Flowering scales glabrous or merely hispidulous. 



Leaves very rough throughout. g, A. pseudorepens. 



Leaves smooth beneath, more or less hirsute above. 



10. A. repens. 



1. Agropyron Richardsonii Schrad. Culms 6-10 dm. tall; sheaths smooth 

 and glabrous; leaves erect, 8-20 cm. long, 4-8 mm. wide, very rough; spike stout, 

 strict, often one-sided, 9-15 cm. long, 8-10 mm. thick; spikelets crowded, 3-5- 

 flowered, the empty scales firm, rough on the nerves, short-awned, the flowering 

 scales glabrous, with an awn usually 2-3 times as long as themselves. From 

 Minn, to the Saskatchewan, south to Neb. and Colo. July-Aug. 



2. Agropyron caninum (L.) R. & S. AWNED WHEAT-GRASS. FIBROUS- 

 ROOTED WHEAT-GRASS. (I. F. f. 528.) Culms 3-9 dm. tall; sheaths glabrous or 

 the lower sometimes pubescent; leaves 7.5-22.5 cm. long, 2-6 mm. wide, smooth 

 beneath, rough above; spike 7.5-20 cm. in length, nodding at the top; spikelets 

 3-6-flowered; empty scales 9-12 mm. long, 3~5-nerved, acuminate, awn-pointed 

 or bearing an awn 2-6 mm. long; flowering scales 8-io mm. long, usually sca- 

 brous toward the apex, acuminate into an awn sometimes twice their own length.. 

 N. B. to Br. Col., south to N. Car., Tenn. and Colo. Also in Europe and Asia. 

 Native northward; southward locally naturalized from Europe. July Aug. 



3. Agropyron tenerum Vasey. SLENDER WHEAT-GRASS. (I. F. f. 527.) 

 Glabrous; culms 6-9 dm. tall. Sheaths glabrous; leaves 7.5-25 cm. long, 2-4 mm. 

 wide, flat or involute, rough; spike 7.5-17.5 cm. in length, usually narrow and 

 slender; spikelets 3-5-flowered; empty scales 8-12 mm. long, acuminate or short- 

 awned, 3~5-nerved, scarious on the margins; flowering scales 1012 mm. long, 

 5 -nerved, awn-pointed or short-awned, scarious on the margins, often rough toward 

 the apex. In dry soil, Lab. to Br. Col., south to N. H., Vt., Kans., Colo, and Cal. 

 July-Aug. 



4. Agropyron violaceum (Hornem.) Vasey. PURPLISH WHEAT-GRASS. 

 (I. F. f. 526.) Culms 1.5-6 dm. tall; leaves 5-15 cm. long, 2-6 mm. wide, flat or 

 involute, rougher sometimes smooth beneath; spike 2.5-10 cm. in length, occa- 

 sionally longer, 4-6 mm. broad; spikelets 3 6- flowered; empty scales broad, 

 usually purplish, scarious on the margins, 5-7-nerved, 8-12 mm. long, acute or 

 acuminate, sometimes awn-pointed, rarely long-awned; flowering scales often 

 purplish, 5-7 -nerve d> scarious on the margins, 8-12 mm. long, acuminate or short- 



