TKIANDRIA. DIGTMA. 41 



before evolution; llgula entire, conspicuous. Calix 2- 

 valved, 1 -flowered, valves membranaceous, about twice 

 the leng-th of the corolla, ventricose and g-ibbous, above 

 the corolla contracted; both 3-nerved, the lateral nerves 

 only about one third the length of the glume, the central 

 nerve ending- in a cusp or short awn margined by the 

 glume at its base, nerves a little pubescent. Corolla 2- 

 valved, short, nearly oval, in fruit almost splierical, valves 

 coriaceous, vested with an exserted silky villus, extend- 

 ing bevond the corolla, the dorsal valve teraiinated by a 

 triquetrous pungent deciduous awn scarcely the length 

 of the calix, at first perfectly erect, afterwards a little 

 bent; the inner valve entirely enclosed by the outer and 

 witliout awn. Stamina 3, scarcely exserted beyond the 

 valves of the corolla; anthers small, brown, bifid at both 

 extremities, above terminated by small pubescent tufts. 

 Stifle 1. Siio-mas 2, short, hirsutely villous. Ovarium 

 sheathed by a 3-leaved perisporium (or nectary). Seed 

 nearly spherical. 



This genus is very nearly allied to Ori/zopsis, but at 

 tlie same time sufficiently distinct both in habit and cha^ 

 racier; having a culm with remarkable long sheathing 

 and almost filiform subulate leaves, a dichotomous spread- 

 ing panicle, a ventricose, coarctate, awned calix twice the 

 length of the coiolla, which last is furnished with a deci- 

 duous awn, and a long silky villus. 



Habitat. On the grassy plains of the Missouri, 

 from the Arifcaree village to the Northern Andes? Flowers 

 in June and July, 



Order 2. — Digyma. 



f Calix 1 -JI 07V ered 9 flowers scattered, 



64. MUHLENBERGIA. Schrcber. Dilepy- 



RUM. Michaux, 



Calix very minute, truncated, 2-va1ved, un- 

 equal. Corolla 2-valved^ hairy at the base, ex- 

 terior valve terminating in a slender awn. 

 (^Style 1?) 



Culm slender, leafy, terminating in a compounded 

 racemose appresscd panicle. Calix persistent, as in 

 .i^rostis, but extremely minute; like an obtuse unequaiiy 

 bifid scale in the J[. dijfusa; in the .V. erecta one of the 

 valves is rather long and acute, according to the olser- 

 E 2 



