628 GRAMINE^. (grass FAMILY.) 



Var. alterniflora, Gray. Spikes more slender (3 - 5' long), and the spike- 

 lets remotish, barely overlapping, the rhachis continued into a more conspic- 

 uous bract-like appendage ; larger glume indistinctly 5-nerved ; otherwise as 

 in the preceding form, into which it passes. — Common with the last ; also 

 Onondaga Lake, J. A. Paine. 



2. BECKMANNIA, Host. (PI. 15.) 

 Spikelets jointed upon the pedicels, 1 - 2-tlowered (only one fertile), obovate 

 and laterally compressed, imbricated in 2 rows upon one side of the angled 

 rhachis of a spike. Glumes 3 or 4, the 2 lower strongly concave and carinate, 

 obtuse or acutish, the 1 or 2 flowering glumes narrower, lanceolate, acute or 

 acuminate and a little exserted, becoming rather rigid and with the thin palet 

 enclosing the oblong grain. — A stout erect subaquatic perennial, with the 

 short spikes erect and simply spicate or in a strict narrow panicle. (Named 

 for John Beckmann, professor of botany at Goettingen.) 



1. B. erucseformis, Host, var. unifldra, Scribn. Glumes 3 and spike- 

 lets l-flowered; spikes (6" long or less) panicled. — N. W. Iowa, W. Minn., 

 and westward. The Old World form, which also is found in the far north- 

 west, has 2-flowered spikelets. 



3. pXSPALUM, L. (PI. 13.) 



Spikelets spiked or somewhat racemed, in 2 - 4 rows on one side of a flat- 

 tened or filiform continuous rhachis, jointed upon very short pedicels, plano- 

 convex, awnless, l-flowered. Glumes 3 (rarely only 2), the terminal one 

 flowering. Flower coriaceous, mostly orbicular or ovate, flat on the inner 

 side, convex on the outer. Stamens 3. Spikes one or more, at or toward the 

 summit of an elongated peduncle. {UaaTrdAos, a Greek name for Millet.) 

 * Spikes with a (1") broad and thin membranaceous or foliaceoiis and keeled 



rhachis, the incurved margins partly enclosing the small two-rowed spikelets. 



(Smooth, aquatic, or nearly so, decumbent or floating.) 



1. P. flilitailS, Kunth. Annual; leaves lanceolate, flat (3 - 8"), broad ; 

 spikes numerous in a raceme, the rhachis somewhat projecting beyond the 

 minute and slightly pubescent spikelets into a tapering point, scabrous on the 

 back. — Eiver-swamps, Va. to S. 111., Mo., and southward. Sept., Oct. 



2. P. Walterianum, Schultes. Perennial; leaves linear, short ; spikes 

 3-7, the lowest partly included in the sheath of the uppermost leaf, the rha- 

 chis blunt; spikelets glabrous. — Low or wet grounds, N. J. (Cape May^ 

 Nuttall)^ Del., and southward. 



* * Spikes with a narrow wingless rhachis ; perennials, or mostly so. 

 t^ Spikelets very obtuse, orbicular ; spikes one terminal and often 1-5 lateral. 



S. P. setaceum, Michx. Culm ascending or decumbent (1 -2° long); 

 slender; leaves (2" wide, flat) and sheaths clothed with soft spreading h&irs; 

 spikes very slender (2 - 4' long), smooth, mostly solitary on a long peduncle, and 

 usually one from the sheaths of each of the upper leaves on sho7-t peduncles or in- 

 cluded ; spikelets (-^" wide) narrowly 2-rowed. — Sandy fields; common from 

 E. Mass. to 111., and southward. Aug. 



4. P.- Igeve, ^lichx. (PI. 13, fig. l -3.) Bright green, sparingly villous, 

 rather stout ; stems somewhat decumbent ; leaves and spikes widely spread- 



