158 POACEAE 



115. LOLIUM L. 



Annual or perennial grasses, with flat leaf-blades and terminal simple usually elongated 

 spikes. Spikelets with the edge (backs of the scales) to the rachis, scattered, erect, alter- 

 nate, sessile and solitary in the rachis excavations, compressed, several-many-flowered, the 

 flowers perfect or the upper ones imperfect, the rachilla articulated between the flowers. 

 Scales rigid, rounded on the back, obtuse to acuminate, awned or awnless, the nerves con- 

 nivent above or confluent into the awn, the lower scale of the lateral spikelets and the 2 

 lower scales of the terminal spikelet empty, narrow, longer than the remaining scales, thin 

 flowering scales short, imbricated ; palet shorter than the scale, 2-keeled. Stamens 3. 

 Styles distinct, very short. Stigmas plumose. DARNEL. RYE GRASS. 



Empty scale shorter than the spikelet. 



Flowering scales awnless. 1. L. perenne. 



Flowering scales awned. 2. L. Italicum. 



Empty scale equalling or extending beyond the flowering scales. 3. L. temulentum. 



1. Lolium per6nne L. Stems 1.5-8 dm. tall : leaf -blades 5-13 cm. long, 2-4 mm. 

 wide : spike 7-20 cm. long : spikelets 5-10-flowered, 8-12 mm. long, the empty scale 

 strongly nerved, the flowering scales 4-6 mm. long, acuminate, awnless. 



In waste places and cultivated ground, almost throughout the northern United States. Natural- 

 ized from Europe. Summer. 



2. Lolium Itctticum A. Br. Stems 6-10 dm. tall : leaf-sheaths glabrous ; blades 

 1-2 dm. long, 3-7 mm. wide : spikes 2-3 dm. long: spikeieis 20-30, i. 5-2 cm. long, the 

 flowering scales bearing an awn equalling or a little shorter than the body. 



In fields and waste places, sparingly introduced. Naturalized from Europe. Summer. 



3. Lolium temul6ntum L. Stems 6-12 dm. tall : leaf-blades 1-2.5 dm. long, 2-6 

 mm. wide, rough above : spike 1-3 dm. long : spikelets 4-8-flowered, 1-2 cm. long, the 

 empty scale strongly nerved, the flowering scales awned or awnless. 



In waste places and cultivated ground, New Brunswick to Michigan, Georgia and Kansas. Summer 



116. AGROPYRON J. Gaertn. 



Annual or perennial grasses, with flat or convolute leaf-blades and terminal usually 

 rigid 2-4-sided spikes. Spikelets compressed, with the side (edge of the scales) toward 

 the continuous or rarely articulated, rachis, sessile, alternate, single in the rachis excava- 

 tions, appressed or oblique to tlje rachis, several-many-flowered, the flowers perfect or the 

 upper ones imperfect, the rachilla articulated between the flowers. Scales several-many, 

 the 2 lower empty, the flowering ones broader, rigid, rounded on the back, obtuse to 

 acuminate, awned or awnless, the nerves connivent at the apex or confluent into the awn, 

 the remaining scales if any empty ; palet shorter than the scale, 2-keeled, the keels usually 

 ciliate. Stamens 3. Styles very short, distinct. Stigmas plumose. WHEAT GRASS. 



Spikelets much compressed, lanceolate to ovate, ascending. 1. A. occidental. 



Spikelets nearly terete, linear, erect. 2. A. repens. 



1. Agropyron occidentale Scribn. Pale green, glaucous. Stems 4-12 dm. tall, 

 from a slender creeping rootstock : leaf-blades erect, 5-20 cm. long, 4-8 mm. wide, rough 

 above, smooth beneath, becoming involute when dry : spike strict, 1-2 dm. long :spikelets 

 crowded, diverging from the rachis, 1.25-2.5 cm. long, 6-12-flowered, the empty scales 

 acuminate, awn-pointed, hispidulous on the keel, the flowering scales 10-12 mm. long, 

 acute, sometimes awn-pointed, glabrous or sparingly pubescent. 



On prairies and high plains, Manitoba and Minnesota to Oregon, Missouri and Texas. Summer. 



2. Agropyron repens ( L. ) Beauv. Stems 3-12 dm. tall, from a long rootstock : 

 leaf-blades 7-30 cm. long, 2-10 mm. wide, smooth beneath, hirsute above : spike 5-20 cm. 

 long, strict : spikelets 3-7 -flowered, the empty scales strongly 5-7-nerved, usually acute or 

 awn-pointed, sometimes obtuse, the flowering scales glabrous, acute or short -awned. 



In fields and waste places, almost throughout North America. Naturalized from Europe. Summer 

 and fall. COUCH GRASS. QUITCH GRASS. 



117. HORDEUM L. 



Annual, rarely perennial, grasses, with flat leaf-blades and terminal cylindric usually 

 dense spikes which are often concealed by the long awns. Spikelets in alternate 3's 

 (rarely in 2's) at each node of the articulated rachis, sessile or short-pedicelled, the lateral 

 often much -reduced, 1-flowered, the flower perfect, or in the lateral spikelets often imper- 



