MANUAL OF THE GRASSES OF THE UNITED STATES 



413 



open forest, southern California. Used 

 by Indians in basket making. 



69. Muhlenbergia mundula I. M. 



Johnston. (Fig. 588.) Similar to the 

 preceding; ligule 1 to 2 mm. long; 

 panicle similar, but lower branches 

 not more than 4 cm. long; spikelets 

 3 to 4 mm. long, the glumes shorter 

 than the lemma or sometimes about 

 equaling it. % (This and the next 

 species included in M. rigens in Man- 

 ual, ed. 1.) — Rocky canyons and gul- 

 lies, Nevada, New Mexico, Arizona, 

 and northern Mexico. This and the 

 following doubtfully distinct from M. 

 rigens. Many intermediates are found. 



70. Muhlenbergia marshii I. M. 

 Johnston. (Fig. 589.) Often smaller 

 than M. rigens, differing in the minute 

 ligule and narrower, usually awn-" 

 tipped glumes and lemma. % — 



Figtjbe 589. — Muhlenbergia marshii. Glumes and 

 lemma, X 10. (Type collection.) 



Rocky stream banks and canyons, 

 Texas and northern Mexico. 



83. SPOROBOLUS R. Br. Dropseed 



Spikelets 1-flowered, the rachilla disarticulating above the glumes; glumes 

 1-nerved, usually unequal, the second often as long as the spikelet; lemma 

 membranaceous, 1-nerved, awnless; palea usually prominent and as long as the 

 lemma or longer; caryopsis free from the lemma and palea, falling readily 

 from the spikelet at maturity, the pericarp free from the seed, usually thin and 

 closely enveloping it, but readily slipping away when moist. Annuals or 

 perennials, with small spikelets in open or contracted panicles. Type species, 

 Sporobolus indicus. Name from Greek spora, seed, and ballein, to throw, 

 alluding to the free seeds. In some species of this genus the palea splits at 

 maturity, giving the impression of an extra lemma. The first glume is early 

 deciduous in some species. The size of the spikelets is often variable in the 

 same panicle. 



Most of the perennial species are palatable forage grasses, but few of them 

 are abundant enough to be of importance. Two species of the Southwest, 

 S. airoides and S. wrightii, are valuable grasses in the arid and semiarid 

 regions; S. interruptus is common on the Arizona Plateau; and the widely 

 distributed S. cryptandrus is also important. The seed of S. flexuosus and S. 

 cryptandrus have been used for food by the Indians. 



la. Plants annual. 

 Panicles pyramidal, many-flowered, the lower branches verticillate. 



Spikelets appressed, short-pediceled, 1.5 to 1.7 mm. long; panicle branches densely 



flowered 1. S. pulvinatus. 



Spikelets spreading, long-pediceled, 1.8 to 2 mm. long; panicle branches loosely few- 

 flowered __ _ 2. S. PATENS. 



Panicles narrow, spikelike, few-flowered, usually included in the sheaths. 



Lemma pubescent - 3. S. vaginiflorus. 



Lemma glabrous _ _._ 4. S. neglectus. 



lb. Plants perennial. 

 2a. Plants producing creeping rhizomes. Panicle narrow or spikelike. 



Rhizomes extensively creeping; leaves numerous, crowded, the blades involute, con- 

 spicuously distichous; panicle spikelike 10. S. virginicus. 



