150 BULLETIN 772, U. S. DEPARTMENT OF AGRICULTURE. 



panicles. Species about 95, in the warm regions of both hemispheres, 

 most abundant in America ; 36 species in the United States. 



Type species : Agrostis indica L. 



Sporobolus R. Br., Proclr. Fl. Nov. Holl. 169. 1810. Three species are de- 

 scribed, & indicus, 8. elongatus, and 8. pulchellus. Brown states that Sporobo- 

 lus includes Agrostis species of Linnaeus. Of the three species described by 

 Brown only the first was known to Linnaeus and included by him under Agrostis. 

 Hence the first species is chosen as the type. 



Agrosticula Raddi, Agrost. Bras. 33, pi. 1, f. 2. 1823. Type A. muralis, the 

 only species described. 



Bennetia Raf., Bull. Bot. Seringe 1: 220. 1830. Afirostis jmicea Michx. is 

 the only species included. This is Sporobolus gracilis (Trin.) Merr. 



Crystostachys Stend.. Syn. PI. Glum. 1: 181. 1854. The type is C. rapinata. 

 the only species described. From the description this appears to be Sporobolus 

 vaginaeflorus. 



Bauchea Fourn.. Mex. PI. 2: 87. 1886. Type B. karwinskyi, the only species 

 described. This is Sporobolus u:rightii. 



The fruit is free from the lemma and palea, and falls readily from 

 the spikelet at maturity. Because of this character the species have 

 been called drop-seed grasses. The genus differs from Muhlenbergia 

 in having 1 -nerved awnless lemmas and from Agrostis in having 

 lemmas as long as the glumes or longer and as firm. 



Four species of the United States are annual. One of them, 

 Sporobolus vaginae-flams (Torr.) Wood, is called poverty grass, 

 because it grows in sterile soil. This has narrow panicles, partly or 

 wholl}' inclosed in the sheaths. Several of the perennial species have 

 creeping rhizomes. One of these, S. virginicus (L.) Kunth, is a 

 common seashore grass in the Southern States. It has erect stems 

 6 to 10 inches tall, with spikelike panicles of pale spikelets. The 

 other species of the genus are erect bunch-grasses. Sporobolus ~ber- 

 teroanus (Trin.) Hitchc. and Chase (fig. 84), with long, slender, 

 spikelike panicles, is common in the Southern States (S. indicus 

 of the manuals, not S. indicus (L.) R. Br.). This species is 

 called smut-grass, because the inflorescence is frequently affected 

 with a black fungus. The glumes are about equal and much 

 shorter than the lemma. Sporobolus wyptandrus (Torr.) Gray 

 (fig. 85) is common on sandy soil, especially in the interior of 

 the country. This has very small spikelets in panicles sometimes 

 partly inclosed in the upper sheath, only the upper portion 

 spreading, or even entirely inclosed in the swollen sheaths. There 

 is a conspicuous tuft of hairs at the summit of the sheaths. In 

 winter the leaves and stems become fibrous and much frayed out by 

 the wind. 



Two species of the Southwest are important forage grasses in the 

 arid and semiarid regions. Sporobolus cdroides Torr. (fig. 86), 

 growing in dense, tough clumps, the stems 1 or 2 feet high, and with 

 large spreading panicles, is found on somewhat alkaline soil and is 

 called bunch-grass or alkali saccaton. It ranges from Nebraska to 



