WOOTON AND STANDLEY FLORA OF NEW MEXICO. 45 



Spikeleta oval or obovate; fruit chartaceous, 

 rigid, the lemma margins inrolled, not 

 hyaline. 

 First glume present; spikelets panicled, 



rarely in racemes 17. Panicum (p. 56). 



First glume obsolete; spikeleta in racemes. 

 Spikelet with a swollen ringlike cal- 

 lus below; fruit awn-tipped... 15. Eriochloa (p. 54). 

 Spikelets without a callus; fruit not 



awned 16. Paspalum (p. 55). 



Tribe V. PHALARIDEAE. 



Panicles dense and contracted; sterile lemmas minute. 21. Phalaris (p. 61). 

 Panicles loose and open; sterile lemmas inclosing 



staminate flowers 22. Savastana (p. 61). 



Tribe VI. AGROSTIDEAE. 



Lemmas indurated at maturity, closely inclosing the 

 grain . 

 Spikelets in pairs, one perfect, the other staminate 



or sterile (in spikelike panicles) 23. Lycurus (p. 62). 



Spikelets not in pairs, all perfect. 



Lemma 3-awned (2 of the awns sometimes very 



small) 24, Aristida (p. 62). 



Lemmas 1-awned or awnless. 



Awns twisted and bent 25. Stipa (p. 65). 



Awns not twisted, or wanting. 



Lemmas narrow; awns, when present, 



persistent 26. Muhlenbergia (p. 68). 



Lemmas broad; awns deciduous 27. Oryzopsis (p. 72). 



Lemmas usually thin at maturity, at least more delicate 

 than the glumes; grain loosely inclosed. 

 Glumes conspicuously compressed-keeled; panicle 

 dense and spikelike, cylindrical. 

 Rachilla jointed above the glumes, these per- 

 sistent; lemma awnless 28. Phleum (p. 73). 



Rachilla jointed below the glumes, these fall- 

 ing with the spikelets; lemma awned.. 29. Alopecurus (p. 73). 

 Glumes not compressed-keeled; panicles mostly 

 open and spreading, rarely crowded and 

 spike like. 

 Panicle spikelike, elongated, 30 cm. long or 



more 30. Epicampes (p. 74). 



Panicle not elongated. 



Spikeleta articulated below the glumes, 

 falling entire. 



Glumes awned; panicles dense 33. Polypogon (p. 77). 



Glumes awnless; panicles open 34. Cinna (p. 78). 



Spikelets articulated above the glumes, 

 Ihese persistent after the fall of the 

 florets. 



