Genus 103. 



GRASS FAMILY. 



283 



103. AGROPYRON J. Gaertn. Nov. Comm. Petrop. 14: Part 1, 539. 1770. 



Annual or perennial grasses, with flat or involute leaf-blades and terminal spikes. Spike- 

 lets 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, 5-7-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 50 species, in all temperate regions. Type species : Agropyron cristatum J. Gaertn. 



Culms not densely tufted ; plants with creeping rootstocks or stolons. 

 Spikelets glabrous or hispidulous. 

 Empty scales strongly 5-11-nerved. 



Empty scales attenuate into an awn or awn-point ; plant green. 



Under surface of the leaf-blades smooth, the upper surface often pubescent ; an 



introduced weed. 1. A. repens. 



Under surface of leaf -blades very rough, the upper surface glabrous ; a western grass. 



2v A. pseudorepens. 

 Empty scales rather abruptly narrowed to a blunt point ; plant glaucous. 



3. A. pungens. 

 Empty scales usually faintly 1-3-nerved, sometimes 5-nerved. 4. A. Smithii. 



Spikelets densely pubescent. 3. A. dasystachyum. 



Culms densely tufted ; plants with no rootstocks or stolons. 

 Awn shorter than the flowering scale. 



Empty scales broad above the middle. 6. A. biflorum. 



Empty scales narrowed from below the middle. 7. A. tenerum. 



Awn much longer than the flowering scale. 8. A. caninum. 



i. Agropyron repens (L.) Beauv. Couch- 

 grass. Quitch-grass. Fig. 686. 



Triticum repens L. Sp. PI. 86. 1753. 

 Agropyron repens Beauv. Agrost. 146. 1812. 



Culms i°-4° tall, from a long jointed running root- 

 stock. Sheaths usually shorter than the internodes, 

 smooth and glabrous ; ligule very short ; blades 3'-i2' 

 long, 1 "-5" wide, smooth beneath, rough above; spike 

 2'-%' in length, strict; spikelets 3-7-flowered ; empty 

 scales strongly 5-7-nerved, usually acute or awn- 

 pointed, sometimes obtuse; flowering scales smooth 

 and glabrous, acute or short-awned at the apex. 



In fields and waste places, almost throughout North 

 America except the extreme north. Naturalized from 

 Europe and often a troublesome weed. Very variable. 

 Native also of Asia. Quitch-, Twitch-, or Witch-grass. 

 Stroil. Quichens. Squitch. Wickens. Shelly-, Knot-, 

 Dog-, Shear- or Quack-grass. Blue-joint. Slough- or 

 Pond-grass. False Wheat. Colorado blue-grass. July- 

 Sept. 



2. Agropyron pseudo-repens Scribn. & Sm. 

 False Couch-grass. Fig. 687. 



Agropyron pseudorepens Scribn. & Sm. Bull. U. S. Dept. 

 Agric. Div. Agrost. 4: 34. 1897. 



Light green. Culms i°-3° tall, erect, smooth and 

 glabrous, from a running rootstock; sheaths shorter 

 than the internodes, smooth; ligule a short mem- 

 branous ring; blades' erect, prominently nerved, 

 rough on both surfaces, acuminate, the culm leaves 

 3'-8' long, 2"-3" wide, the basal leaves about one- 

 half as long as the culms ; spikes 3'-8' long, strict ; 

 spikelets $"-%" long, 3-7-flowered, a little com- 

 pressed, appressed to the rachis which is hispidulous 

 on the margins; empty scales lanceolate, equalling or 

 somewhat shorter than the spikelet, acuminate and 

 often awn-pointed, 5-7-nerved, the nerves hispidu- 

 lous ; flowering scales 5-nerved, roughish toward the 

 apex, usually awn-pointed. 



Rich river bottoms, British Columbia and Athabasca, 

 to Arizona, Texas, Missouri and Iowa. July-Aug. 



