1. M. mùtica, Walt. ([Pl. 10.]) Slender, with usually narrow leaves, the panicle often reduced to a simple raceme; lower glumes nearly equal and almost equalling the spikelet; fertile flowers usually 2; flowering glumes broad, smooth, obtuse.—Rich soil, Penn. to Fla., west to Wisc., Iowa, and Tex.
2. M. diffùsa, Pursh. Taller, 2½–4° high, with mostly broader leaves and a more usually compound and many-flowered panicle; lower glumes more unequal, the outer very broad; fertile flowers usually 3; flowering glumes somewhat scabrous and more acute. (M. mutica, var. diffusa, Gray.)—Penn. to Ill., and southward.
(Addendum) 3. M. Pórteri, Scribn. Tall and slender; panicle very narrow, the slender branches erect or the lower slightly divergent; pedicels flexuous or recurved, pubescent; glumes very unequal and shorter than the spikelet; fertile flowers 3–5, the glumes scabrous.—Mountains of Col. and southward; reported from Cass Co., Neb. (J. G. Smith).
59. DIARRHÈNA, Raf. ([Pl. 10.])
Spikelets several-flowered, smooth and shining, one or two of the uppermost flowers sterile. Empty glumes ovate, much shorter than the flowers, coriaceous; the lower much smaller; flowering glume ovate, convex on the back, rigidly coriaceous, its 3 nerves terminating in a strong and abrupt cuspidate or awl-shaped tip. Squamulæ ovate, ciliate. Stamens 2. Grain very large, obliquely ovoid, obtusely pointed, rather longer than the glume, the cartilaginous shining pericarp not adherent to the seed.—A nearly smooth perennial, with running rootstocks, producing simple culms (2–3° high) with long linear-lanceolate flat leaves toward the base, naked above, bearing a few short-pedicelled spikelets (2–3´´ long) in a very simple panicle. (Name composed of δίς, two, and ἄῤῥην, man, from the two stamens.)
1. D. Americàna, Beauv. Shaded river-banks and woods, Ohio to Ill., and southward. Aug.
60. UNÌOLA, L. Spike-Grass. ([Pl. 11.])
Spikelets closely many-flowered, very flat and 2-edged; 3–6 of the lowest glumes empty, lanceolate, compressed-keeled; flowering glume coriaceo-membranaceous, strongly laterally compressed and keeled, striate-nerved, usually acute or pointed, entire, enclosing the much smaller compressed 2-keeled palet and the free laterally flattened smooth grain. Stamen 1 (or in U. paniculata 3).—Upright smooth perennials, growing in tufts from strong creeping rootstocks, with broad leaves and large spikelets in an open or spiked panicle. (Ancient name of some plant, a diminutive of unio, unity.)
[*] Spikelets large (½–2´ long), ovate or oblong, 9–30-flowered; panicle open.
1. U. paniculàta, L. (Sea Oats.) Culm and panicle elongated (4–8° high); leaves narrow, when dry convolute; spikelets ovate, short-pedicelled; glumes glabrous, bluntish, several of the lower sterile; stamens 3.—Sand-hills on the sea shore, S. Va. and southward.