These are tall, annual or perennial grasses, with leafy stems and narrow leaves. The spikes are few or many, solitary or panicled, with a jointed usually fragile rachis; the joints are rounded or compressed, hollowed on one side and excavated at the tip. The spikelets are usually binate, one-sessile closing or sunk in the cavity of the joint and the other pedicelled, smaller than the sessile or rudimentary with the pedicel usually adnate to the joints and equal to or shorter than it. The sessile spikelets are bisexual, 1- to 2-flowered, equal to or shorter than the joint and four-glumed. The first glume is coriaceous dorsally flattened, obtuse, margins narrowly incurved. The second glume is thinner than the first, broadly ovate, acute and gibbously convex. The third glume is hyaline, ovate, acute, male or neuter, with a membranous palea. The fourth glume is hyaline, bisexual, broadly ovate, acute with a hyaline, ovate-lanceolate palea. There are three stamens with linear anthers. There are two cuneate lodicules. Styles are two with laterally exserted stigmas. The grain is broadly oblong. The pedicelled spikelets are smaller than the sessile, male or neuter, with four glumes. The first glume is herbaceous, many-nerved, ovate-acute, minutely bifid at the apex. The second, third and the fourth are more or less similar to those of the sessile spikelet. KEY TO THE SPECIES. Spike solitary, the first glume of the sessile spikelet broadly winged. R. Myurus. Spikes fascicled, the first glume of the sessile spikelet narrowly winged. R. exaltata. =Rottboellia Myurus, _Benth._= This is a tufted perennial with creeping stems which branch freely into ascending compressed branches, 10 inches to 2 feet high. The _leaf-sheath_ is quite glabrous and compressed. The _ligule_ is a short ciliate membrane. _Nodes_ are glabrous. _The leaf-blade_ is flat, linear, acute, glabrous, 2 to 6 inches long.