60 American Midland Naturalist Monograph No. 2 



41. Oryzopsis Michx. — Rice Grass 



1. Leaves narrow, involute; spikelets (excluding the awns) 3-4 mm. long; dry 

 soil, rare O. pungens (Torr.) Hitchc. 



1. Leaves flat, 4-15 mm. wide; spikel'ets (excluding the awns) 6-8 mm. long. 

 2. Leaves scattered along the stem, the upper surface pubescent; panicle 



15-30 cm. long; rocky woods, not common. Aug.-Sept 



- O. racemosa (Sm.) Ricker 



2. Leaves mostly basal, merely scabrous above; panicle 5-8 cm. long. Cook 

 Co., Shtpman in 1877 0. asperifolia Michx. 



42. Stipa L. 



S. spartea Trin. Porcupine Grass. Sandy soil, locally throughout 111., except 

 the s. counties. May-June. 



43. Aristida L. — Three-awned Grass 

 1. Awns jointed to the lemma. 



2. Awns united in a spiral column 6-15 mm. or more in length; sandy soil. 

 Aug.-Sept A. tuberculosa Nutt. 



2. Awn-column about 2 mm. long; sandy soil, not common. Mason Co., 



Behb in 1861 A. desmaiitba Trin. & Rupr. 



1. Awns distinct, not jointed to the lemma. 



3. Central awn much longer than the lateral awns, these erect. 

 4. Central awn spirally coiled at base. 



5. Second glume 7-9 mm. long, equalling or slightly longer than the 



first; roadsides and fields in centr. and s. 111. Aug. -Oct 



A. dichotoma Michx. 



5. Second glume 10-15 mm. long, much longer than the first. 



6. Lateral awns 1-2 mm. long, straight, erect; dry ground, not com- 

 mon. Sept. -Oct A. curtissii (Gray) Nash 



6. Lateral awns 2-7 mm. long, spreading; dry ground, n.w. Ill 



A. basiramea Engelm. 



4. Central awn not coiled. 



7. Lemma 4-5 mm. long; fields and roadsides, chiefly in the s. and w. 

 parts of the state. [A. gracilis Ell.} A. longespica Poir. 



7. Lemma 2-3 cm. long; fields and roadsides, in the s. half of the state. 

 Aug.-Sept. A. ramosissivia Engelm. 



3. Central awn subequal in length with the lateral ones. 



8. Glumes 8-11 mm. long; awns not over 2.5 cm. long; sandy soil. Aug.- 

 Sept A . purpurascens Poir. 



8. Glumes 2-3 cm. long; awns 4-7 cm. long; fields, open woods, and 

 roadsides. Aug.-Oct A. oligaiitha Michx. 



44. Eleusine Gaertn. 



E. indica (L.) Gaertn. Goose Grass, Waste places, roadsides, and culti- 

 vated ground; nat. from Eurasia. July-Oct. 



