| Tall reed-like grasses with silvery panicles. Flowering glumes covered with long hairs, membranous. Rhachilla long, glabrous | 25. Arundo. |
| Spikelets 3–5 flowered, usually rounded on the back. Flowering glumes 2–3-toothed, middle tooth often mucroniform or slightly awned | 26. Triodia. |
| Panicle spiciform. Spikelets 2–5-flowered, shining, compressed. Flowering glumes scarious, mucronate or shortly awned | 27. Kœleria. |
| Spikelets 2–many-flowered, compressed. Flowering glumes keeled at the back, acute or obtuse, awnless, often (together with the rhachilla) clothed at the base with tangled hairs. Hilum punctiform | 28. Poa. |
| Spikelets 3–many-flowered. Flowering glumes rounded at the back, obtuse, awnless, 5–9-nerved. Lodicules distinct. Hilum punctiform | 29. Atropis. |
| Spikelets 2–many-flowered. Flowering glumes rounded on the back, more rigid than in Poa, acute or awned. Ovary naked or hairy. Hilum long, linear | 30. Festuca. |
| Spikelets 3–many-flowered. Flowering glumes rounded on the back or slightly keeled, mucronate or awned, 5–9-nerved. Ovary villous at the top | 31. Bromus. |
Tribe IX. HORDEÆ.
Spikelets 1–many-flowered, sessile in alternate notches on opposite sides of the rhachis of a simple spike, either solitary or several together. Glumes awned or not.
| Spikelets solitary in the notches of the rhachis, 2–many-flowered, placed flatwise on the rhaihis. Outer glumes conspicuous | 32. Agropyrum. |
| Spikelets solitary (or in non-New-Zealand species in pairs) at the notches of the rhachis, 2–4-flowered, placed flatwise on the rhachis. Empty glumes either wanting or reduced to 2 small bristles | 33. Asperella. |
1. IMPERATA, Cyr.
Tall erect perennial grasses. Leaves long. Panicles long, terminal, densely spiciform or narrow-thyrsiform, silky-silvery. Spikelets all similar, numerous, densely clothed with long silky hairs, usually arranged in pairs on the continuous branches of the panicle, one sessile or almost so, the other distinctly stalked, all 1-flowered. Empty glumes 3, subequal, narrow, membranous, awnless, 3–9-nerved, the 2 outer clothed with long hairs. Flowering glume usually much smaller, hyaline. Palea small, broad, hyaline, nerveless. Lodicules wanting. Stamens 1 or 2. Stigma long, exserted from the tip of the spikelet. Grain oblong, with an embryo half its length or more.
A genus of about 6 species, found in the tropical or warm temperate regions of both hemispheres. One of the New Zealand species is very widely diffused, the other is endemic in the Kermadec Islands.
| Panicle densely spiciform, cylindric, obtuse, shining. Stamens 2 | 1. I. arundinacea. |
| Panicle not so dense, narrow-lanceolate, acuminate, not shining. Stamen 1 | 2. I. Cheesemanii. |
