ACiKOS'liDEAE 



73 



Panicles on lonK peiJuncles. 1<>. M. thurberi. 



I'anicles included in the leaf 



sheaths at the base. H ^' """«• 



Flowering gliiines with long conspicu- 

 ous awns. 

 Leaf sheaths very broad at the base, 

 thin and papery, loose, not close- 

 ly surrounding the stems. 

 Second empty glume 3-toothed; 

 flowering glume pubescent at 

 the top. 

 Empty glumes both acute or acum- 

 inate; flowering glume pubes- 

 cent only below. 

 Leaf sheaths not broad and papery, 

 closely enclosing the stem. 

 Spikelets on long slender pedicels. 

 Spikelets on short stout pedicels or 



without any. 

 Awns about 5 mm. long; plant stout; 



internodes long. 

 Awns about 20 mm. long; plant 

 slender, wiry; internodes short. 



Panicle open and spreading. 



Plant diffusely branched, weakly ascending 

 or decumbent, culms perennial. 

 Secondary branches of the panicle clus- 

 tered; leaves spiny- pointed and stiff. 

 Secondary branches of the panicle single; 

 leaves not spiny-pointed nor very 

 stiff. 

 Basal leaves .short, 2 inches long or 



less, strongly curved or arched. 

 Basal leaves usually longer, not recurv- 

 ed. 

 Awns short, 4 mm. long; leaf-blades 

 2 to 4 inches long; panicle green. 

 Awns longer, 10 to 15 mm. long; leaf- 

 blades about 8 inches long; pani- 

 cle dark purple. 



1. Muhlenbergia vaseyana Scril)ii. In the drier mountains 

 at the southern end ot the State at elevations up to about 6000 feet 

 in the Upper Soiioran Zone. 



2. Muhlenbergia disticho| hyila (Presl.) Munr-). Associated 



with the i)recedln,u- .-pecifs more or less. 



3. Muhlenbergia SChaffaneii Vasey. A small annual occur- 

 ring around seeps in the niounla r.s of the southern part of the 

 State; an the I'l'per Soiioran Zone. 



4. Muhlenbergia Mexicana (L.) Trin. A rather rare 

 species in the niouiiiains ai (lexations ( f 7000 feet or more: in the 

 Transition Zone. 



