- Not floating; spikelet not awned 11. Leersia.
- Floating; spikelets awned 12. Hygrorhiza.
Zoysieæ is another small tribe with half a dozen genera. The inflorescence is either a spike-like raceme or a spiciform panicle. The spikelets are solitary in Perotis, binate in Tragus and grouped in Trachys. There is usually a complete flower in a spikelet and the glumes are membranous. Mature spikelets are deciduous with their pedicels singly in Perotis and in clusters in others.
- Spikelets fascicled unilaterally on a broad rachis, 4-glumed, glumes not echinate 13. Trachys.
- Spikelets binate and all round the rachis, 3-glumed, glumes echinate 14. Tragus.
- Spikelets single, awned and 3-glumed 15. Perotis.
11. Leersia, Sw.
These are tall perennial marsh grasses. The inflorescence is usually a more or less contracted panicle with very slender branches. The spikelets are compressed and consist of only one glume bearing a perfect flower. The solitary flowering glume is chartaceous, awnless, 3- to 5-nerved, the lateral nerves forming the thickened margin of the glume. The palea is narrow, linear-lanceolate, as long as the glume, 3-nerved, rigid, dorsally ciliate, and with hyaline margins. Lodicules are two. Stamens are usually six in number. Styles are short, with plumose stigmas and laterally exserted. Grain is ovoid or oblong, compressed, free within the glume and its palea.
Leersia hexandra, Sw.
This is a slender perennial marsh-grass with stems rooting in the mud and with flexuous floating branches, sending up erect or ascending, weak and slender leafy branches, 2 to 4 feet high.