72 Bulletin VII. 1. 



2. Perennials, 2 to 4 feet high, spikelets 2 to 2^ lines long . . 



I. S. ASPER. 



2. Annuals, with slender diffuse culms 6 to 18 inches high, 

 spikelets ij^ to 2 lines long . . . 2. S. vagin.^florus. 



1. Sporobolus asper Kunth. Prairie-grass. 



Plate XXIII. Figure 90. 



A slender or rather stout perennial, one to three feet high, with 

 usually long, sometimes very long, nearly setaceous leaves. Sheaths 

 smooth; ligule very short; leaf-blade narrow, involute-setaceous 

 above, and in some forms two to three feet long. Panicle con- 

 tracted, linear, two to four or six inches long, partially or wholly 

 enclosed within the leaf-sheaths. Spikelets two to two and one- 

 half lines long, mostly acute; empty glumes obtuse or acute, sca- 

 brous on the keel above, slightly unequal, shorter than the flower- 

 ing glume; flowering glume acute or somewhat rounded at the 

 apex, usually pilose below on the back; palea obtuse and about the 

 length of the glume, or sharp-pointed and much exceeding the 

 glume in length. 



The form with obtuse glumes and with the palea about the length 

 of the flowering glume, is a stout grass, and was recognized by 

 Trinius as a good species under the name of Vilfa Drummondii. It 

 is Vilfa aspera, var. Drummondii Vasey. This variety occurs in Ten- 

 nessee, along with the species growing in dry sandy soils. The 

 very long-leaved form found on the bluffs near Knoxville is. Sporo- 

 bolus longifolius Wood. 



2. Sporobolus vaginaeflorus Wood. Southern Poverty-grass. 



Plate XXIII. Figure 92. 



A slender, cespitose annual, six to eighteen inches high, with 

 very narrow, short leaves, and nearly simple, few-flowered, terminal 

 and axillary panicles, which are mostly enclosed within the some- 

 what inflated leaf-sheaths. Sheaths rigid, usually purplish; ligule 

 very short; leaves involute-setaceous, one to four inches long. 

 Panicles linear, spike-like, about an inch long; spikelets one to two 

 lines long; empty glumes nearly equal, acute, as long as or a little 

 shorter than the ovate and abruptly-pointed floral glume, which is 

 usually a little hairy on the back; palea as long as or a little ex- 

 ceeding the flowering glume. 



Var. 7ninor {S. minor Vasey). Plate XXIII. Figure 91. More 

 slender, with the lateral panicles less strongly developed, and with 

 rather larger and more compressed spikelets. This form seems to 

 be somewhat intermediate between S. vaginceflorus and S. asper. It 

 is much more slender than the latter species, and is at once distin- 

 guished from it by its annual habit. Both forms are common in 

 dry sterile soil, 



3. Sporobolus Indicus R. Br. Smut-grass. 



Plate XXIV. Figure 93. 

 A tufted, wiry, erect perennial, one to three feet high, with sim- 

 ple culms, and narrow, densely-flowered, spike-like panicles, four 



