Holm, Some new ariitomical charncters for certain Gramineae. ]21 



Genera of Gramineae associated with, but not 

 related to Aristida. 



Sporobolus R. Br. 



We have examined the followiug species: 

 S. airoides Torr. (Valleys, Kansas), 

 *S'. argutvs Kth. (In moist soil, river-bottoras, Kansas), 

 S. asper Kth. (On dry rocks at Great Falls of the 



Potomac, Maryland), 

 S. asperifolius Thurb. (Plains, Denver, Colorado), 

 S. hrevicalyx Scribn. (On rocks in the Spruce-Zone 



near Graymont, Clear Creek Caiion, Colorado, at 



10300 ft' alt.), 

 S. hrevifolius Nutt. (Durango, Southern Colorado), 

 S. cryptandrus Gray (Plains, Denver, Colorado), 

 S. cuspidatus Scribn. (Dry hills and uplands, in sterile 



soil, Kansas), 

 S. depauperatus Vas. (Damp places along creeks at 



Twin Lakes near Leadville, Colorado, 9265 ft. alt.), 

 S. indicus R. Br. (Clayish soil, Eustis, Florida), 

 S. junceus Kunth. (High-Pine - woods near Eustis, 



Florida), 

 S. pungens Kunth. (Sandy sea-shore near Cannes, 



France), 

 S. tenacissimus Beauv. (Dry fields, Montevideo, Urug.), 

 aS. vagmaeflorus Vas. (Dry fields near Great Falls of 



the Potomac, Maryland), 

 S. virginicus (L.) Kth. (Sandy sea-shore, Tampa, 



Florida). 



The genus was established by Robert Brown upon species 

 in which the empty glumes are very unequal in length and both 

 shorter than the flowering glume (S. indicus) ; but since his time 

 a number of other species of quite different type have been refered 

 to the genus, namely species of Beauvais' Vilfa, in which the 

 empty glumes are subequal and mostly longer than the flowering 

 glume {V. virginica , pungens etc.). Nevertheless Vilfa, as 

 distinguished by Beauvais, has not gained much recognition 

 and is not regarded as anything but a synonym of Sporobolus in 

 the works ofHackel, Bentham and Hook er. There are 

 cases in which the length of the empty glumes in proportion to 

 the flowering glume does not afford any very distinct character 

 for the Separation of these two genera, especially in cases, where 

 tlie empty glumes are very unequal in length, and the superior 

 of these being of the same length as the flowering glume or, 

 sometimes, even a little longer ; such species would naturally 

 have to be refered to Sporobolus: „with the empty glumes un- 

 equal", while the length of the upper empty glume makes them 

 referable also to Vilfa. However many species are so distinct 

 „ Vilfae'^ that one would not be surprised if some future mono- 

 grapher of Sporobolus should refer them to this genus, Vilfa. 



