718 GRAMINE^ imperata 



PA6PALUM 



Suborder i PANICACE^E R. Br. Verm. Schr. i, 114. 



Spikelets one- or two-flowered, when two-flowered the second or 

 terminal one is perfect and the lower one staminate or neutral. 

 Rachella articulated below the empty glumes the spikelets falling 

 from the pedicels entire either singly or in groups or with the 

 joints of an articulated rachis. 



Tribe 1 Andropogoneoe. Spikelets in spike-like racemes, "2 at 

 each joint of an articulated vachis, one sessile and hermaphrodite, the 

 other pedicellate and either hermaphrodite, staminate, neutral or 

 or reduced to the pedicel only, glumes usually 4, the first 2 empty, 

 larger and much firmer in texture than the others; the third usually 

 with a staminate flower in its axil; the fourth hyaline with a fertile 

 flower in its axil, usually awned. Awn usually twisted or geniculate. 

 1 IMPERATA Cyrill PI. Rar. Ic. ii, 26. (1796.) 



Panicle ^pike-like. Spikelets in pairs on unequal short clavate 

 pedicels or one sessile, both perfect, awnless. Outer empty glumes 

 clothed with long white silky hairs: third and fourth glumes and 

 palet hyaline. Stamens 1 or 2. Stigmas 2. 



I. Hookeri Rupr. (Efvers Vet. Acad. Stockh. 160. Stems 2-4 feet 

 high, simple, smooth, from creeping rootstocks: radical leaves 4-12 inches 

 long, the cauline shorter, decreasing upward : ligule short, ciliate : panicle 

 nearly cylindrical, erect, 6-12 inches long, sometimes interrupted below : 

 hairs densp r straight, about % inch long, giving the peculiar feathery ap- 

 pearance, flecked with the yellow or brown anthers and stigmas. Along 

 streams, eastern Oregon and Nevada to California and Texas. 



Tribe 2 Panicese. Spikelets hermaphrodite, terete or flattened 

 on the back. Glumes 2-4, when 4 there is sometimes a staminate 

 flower or palea in the axil of the third. Axis of the inflorescence not 

 articulated: the rachella being articulated below the glumes, the 

 spikelets falling off singly from their pedicels. 



5 PASPALUM L. Syst. ed. 10, ii, 855. 



Spikes or racemes either solitary, few and digitate or many and 

 panicled. Spikelets in 2-4 rows upon one side of a flattened or 

 filiform jointless rachis, jointed upon their short pedicels, plano- 

 convex, awnless, apparently one-flowered. Glumes 2, nearly 

 equal, few-nerved. Flowering glumes roundish or ovate, coria- 

 ceous, convex and enclosing the palet. Scales 2. Stamens 3. 

 Ovary smooth. Grain enclosed in the glume. 



P. distichum L. Amcen. Acad, v, 391. Rootstock widely creeping, 

 perennial: stems 6-1S inches high, clothed below with the somewhat 

 crowded sheaths: leaves flat, 2-3 inches long, glaucous, rough above: 

 spikes 2, spreading, one se&sile, the other peduncled, 1-1)^ inches long, 

 densely flowered: spikelets in 2 rows, ovate, acute, 1% lines long: glumes 

 3-nerved, more or less pubescent. In moist meadows Oregon to California 

 and the southern Atlantic States : also in Europe. 



3 PANICUM L. Sp. 55. 

 Spikelets 1- or 2-flowered, when 2-flowered the lower one sta. 



