194 



GRAMINEAE. 



VOL. I. 



40. SPOROBOLUS R. Br. Prodr. Fl. Nov. Roll, i : 169. 1810. 



Perennial or rarely annual grasses, with flat or convolute leaf-blades and open or con- 

 tracted panicles. Spikelets generally small, i-flowered, occasionally 2-3- flowered. Scales in 

 the i-flowered spikelets 3, membranous; the 2 outer empty, the first somewhat shorter; the 

 third scale equalling or longer than the empty ones ; palet 2-nerved. Stamens 2-3. Styles 

 very short, distinct. Stigmas plumose. Grain free, 'and often early deciduous. [Greek, 

 referring to the deciduous grain.] 



About 100 species, in tropical and temperate regions, very numerous in America. Besides the 

 following, several others occur in the southern and western United States. Type species : Agrostis 

 indica L. 



1. 5. vaginaeflorns. 



2. S. neglcctits. 



Panicle contracted. 

 Annuals. 



Spikelets 2" long ; flowering scale pubescent. 

 Spikelets iJ4"-ij4" long; flowering scale glabrous. 

 Perennials. 



Plants tufted ; no rootstocks. 



Panicle occupying but a small part of the plant. 

 Leaves glabrous or nearly so. 

 Flowering scale pubescent. 



Palet long-acuminate, much longer than the flowering scale. 3. S. clandcstinus. 

 Palet simply acute, about as long as the flowering scale. 4. S. canorircns. 

 Flowering scale glabrous. 



Spikelets 2" long ; inflorescence slender. 5. 5. Drummondii, 



Spikelets 2y 2 "~z" long; inflorescence stout. 6. S. aspcr. 



Leaves, at least the lower ones, papillose-hirsute. 7. .S 1 . pilosiis. 



Panicle occupying J^-J4 of the plant. 8. S. angnstus. 



Plants with long creeping rootstocks. 9. S. virginicus. 



Panicle open, its branches spreading, at least at maturity (sometimes contracted in no. 15). 

 Annuals. 



Empty scales but little shorter than the flowering scale, usually pubescent. 



10. S. confitsus. 



as long as the flowering scale, glabrous. 



ii. 5". uniflorus. 



Empty scales 

 Perennials. 



Culms tufted ; no rootstocks. 



Spikelets i"-i^" long; empty scales ovate to lanceolate. 

 Panicle branches verticillate. 

 Spikelets Y\" long, green. 

 Spikelets i}4" 1^2" long, purple. 

 Panicle branches alternate. 



Leaf-sheaths naked, or sparingly ciliate at the throat ; panicle usually exserted. 



14. 6". air aides. 

 Leaf-sheaths densely pilose at the throat ; base of the panicle generally included. 



15. S. cryptandnts. 

 Spikelets 2" -3" long ; first scale subulate, much narrower than the second. 



12. 5". argntiis. 



13. S. gracilis. 



Culms from long running rootstocks. 



First scale of the spikelet ^ as long as the second or less. 

 First scale about equalling the second. 



Culms erect, simple ; leaf-blades elongated. 



Culms decumbent and branched below ; leaf-blades short. 



1 6. S. heterolcpis. 



17. S. texanus. 



1 8. S. torreyanus. 



19. 5. asperifolius. 



i. Sporobolus vaginaeflorus Torr. Sheathed 

 Rush-grass. Fig. 464. 



Vilfa vaginaeflora Torr. ; A. Gray, Gram, and Cyp. No. 3. 



1834- 



Sporobolus vaginacflonts Torr. ; Wood, Classbook, 775. 1861. 

 Sporobolus minor Vasey ; A. Gray, Man. Ed. 6, 646. 1890. 



Culms 8'-i8' tall, erect, slender, smooth or scabrous. 

 Sheaths usually inflated, about half as long as the inter- 

 nodes ; ligule very short; blades i" wide or less, smooth 

 and glabrous beneath, scabrous and hairy near the base 

 above, attenuate into a slender involute point, the lower 

 elongated, the upper i'-3' long, setaceous; panicles 3 '-2' 

 in length, the terminal one exserted or sometimes par- 

 tially included, strict, the branches \' long or less, erect, 

 the lateral ones enclosed in the sheaths; spikelets 

 if"-2i" long, the outer scales unequal, acuminate, 

 smooth, the lower one shorter; third scale scabrous, 

 especially toward the apex, about as long as the second 

 and equalling or slightly exceeded by the very acute 

 palet. 



In dry soil, southern Maine to South Dakota, south to 

 Georgia and Texas. Southern poverty-grass. Aug.-Sept. 



