43 



Coleanthus, Seid. 



Spikelets one-flowered, very small, perfect ; outer glumes wanting; 

 flowering glume membranaceous, one-nerved, keeled, acuminate or 

 short aristate ; palet shorter and wider than the flowering glume, 

 two-keeled, acutely two-toothed. A minute annual grass. Stamens 

 2, stigmas 2, sessile. 



1. C. snbtilis, Seid. Sauvie's Island, Oregon. 



Phippsia, Ii. Br. 



Spikelets one-flowered, outer glumes minute, unequal, membrana- 

 ceous ; flowering glume thin, three to four times longer than the 

 outer ones, obscurely three-nerved, keeled, acute; palet a little 

 shorter, two-keeled, two to four toothed at the apex. 

 1. P. algida, Br. Melville Island and Arctic regions. 



Spoeobolus, S. Br. (including Vilfa, Beauv.) 



Spikelets one, rarely two-flowered in a contracted or open panicle. 

 Outer glumes unequal, the lower one shorter, often acute, unawned, 

 one to three-nerved, membranaceous ; flowering glume mostly 

 longer, unawned ; palet about equalling the flowering glume and of 

 the same texture, prominently two-nerved. Seed mostly loose in a 

 hyaline or rarely coriaceous pericarp. 



1. S. airoides, Torr. 



2. S. arundinaceus, Vasey. (Vilfa, Trin.) Alaska and British 



America. 



3. S. arbutus, Kth. var. Arkansana. Texas to Arizona. 



4. S. Arizonicus, Thurb. (S. interrnptus, Vasey.) Arizona. 



5. S. asper, Kth. (Vilfa, Beauv}) New England to Texas. 

 S. asper, var. Hookeri. (Vilfa Hookeri, Trin.) Texas. 



6. S. asperifolius, N. & M. British America to Arizona. 



7. S. Buckleyi, Vasey. Texas. 



8. S. compressus, Kth. New Jersey. 



9. S. cryptandrus, Gray. New England to Mexico. 



This species has an extensive range. It is common in sandy fields 

 in the Northern and Southern States, as well as over all the dry 

 plains west of the Mississippi, extending from British America to 

 Mexico, furnishing a considerable share of the wild pasturage. 



S. cryptandrus, var. flexuosus, Thurb. New Mexico to Arizona. 



