374 MISC. PUBLICATION 200, U. S. DEPT. OF AGRICULTURE 



2. Muhlenbergia minutissima 



(Steud.) Swallen. (Fig. 521.) Annual; 

 culms erect to spreading, branching 

 at base, 10 to 35 cm. tall; blades flat, 

 mostly less than 10 cm. long, about 1 

 mm. wide; panicle half to three- 

 fourths the length of the entire plant, 

 the slender pedicels ascending; spike- 

 lets 1.2 to 1.5 mm. long, the glumes half 

 to two-thirds as long, minutely pilose; 

 lemma minutely silky-pubescent 

 along the midnerve and margins. O 

 (Sporobolus microspermus of Manual, 

 ed. 1.) — Moist sandy or rocky slopes, 

 Montana to Washington south to Tex- 

 as, California, and northern Mexico. 



3. Muhlenbergia fragilis Swallen. 

 (Fig. 522.) Annual; culms geniculate- 

 ascending, freely branching at base, 

 10 to 30 cm. tall; blades flat, mostly 

 2 to 6 cm. long, 1 to 1.5 mm. wide; 

 panicle very diffuse, the capillary 

 branches, branchlets, and pedicels 

 widely spreading or reflexed, fragile; 

 spikelets 1 to 1.1 mm. long, the 

 glumes half to two-thirds as long, 

 glabrous; lemma silky-pubescent on 

 the keel and margins, the palea silky- 

 pubescent between the nerves. 

 — Moist sandy soil and rocky hills, 

 western Texas to southern Arizona, 

 south to central Mexico. 



4. Muhlenbergia sinuosa Swallen. 

 (Fig. 523.) Annual; culms geniculate- 

 ascending, freely branching at base; 

 blades flat, mostly 4 to 10 cm. long, 

 1 to 1.5 mm. wide, minutely pubes- 

 cent on both surfaces; panicle many- 

 flowered, 14 to 22 cm. long, 2 to 6 

 cm. wide, the scabrous branches as- 

 cending, the elongate, capillary pedi- 

 cels sinuous and tangled; spikelets 

 often purple-tinged, 1.5 to 2 mm. 

 long, the glumes about half as long, 

 usually conspicuously pilose; lemma 

 obtuse, delicately silky-pubescent be- 

 low on the midnerve and margins, 

 the broad palea equal. — Moist 

 canyon walls and borders of marshes, 

 New Mexico and Arizona. 



5. Muhlenbergia texana Buckl. 

 (Fig. 524.) Annual, culms delicate, 

 erect or ascending, branching at base, 

 10 to 30 cm. tall, the culms strongly 



Figure 520. — Muhlenbergia wolfii. Plant, X 1; spike- 

 let and floret, X 10. (Hitchcock 7661, Mex.) 



1. Muhlenbergia wolfii (Vasey) 

 Rydb. (Fig. 520.) Annual; culms 

 spreading, branching at base, 6 to 

 25 cm. tall; blades flat, mostly 1 to 

 3 cm. long, 1 mm. wide or less; 

 panicle 2 to 6 cm. long, the simple 

 branches ascending, the short, stiff 

 pedicels appressed along the branches ; 

 spikelets 1 to 1.2 mm. long; glumes 

 glabrous, about half as long as the 

 spikelet; lemma rather turgid, mi- 

 nutely white-silky along the margins. 

 O (Sporobolus ramulosus of Manual, 

 ed. 1.) — Open or wooded slopes, 

 mostly in thin soil, Colorado to 

 northern Mexico and Arizona. 



