164 DIAERHENA. — DACTYLIS. 



27. DIARRHENA— Raf. Diarriiexa. 



GENERIC CHARACTER. 



Spikelets several-flowered, smooth and sliiuing, one 

 one or two of the npj^ennost flowers sterile. Glumes 

 ovate, much shorter than the flowors, coriaceous, the 

 lower one much smaller. Lower palet ovate, convex 

 on the back, rigidly coriaceous, its 3 nerves termina- 

 ting in a strong and abrupt cusi3idate or awd-shaped 

 tip. Squamulse ovate, ciliate. Stamens 2. Grain 

 very large, obliquely ovoid, obtusely pointed, rather 

 longer than the palets, the cartilaginous shining per- 

 icarp not adherent to the seed. A nearly smooth 

 perennial, with running rootstocks, producing sim- 

 ple culms (2 to 3 feet high), with long, linear, lanceo- 

 late flat leaves towards the base, naked above, bear- 

 ing a few short pedicelled spikelets (1-6 to 1-4 inch 

 long) in a very simple panicle. 



Name composed of dis^ two, and arren man, from 

 the two stamens. 



1. D. Americana, Beauv. (Twin Grass). Shaded 

 river banks and woods, Ohio to Illinois, .and south- 

 ward. 



28. DACTYLIS— Linseus. Orclard Grass. 



GET^ERIC CHARACTER. 



Spikelets several-flowered, crowded in one-sided 

 clusters, forming a branching dense panicle. Glumes 

 and lower palet herbaceous, keeled, awn-j)ointed, 



