26. TRIODIA, R. Br.
Perennial grasses, of very various habit. Leaves narrow, rigid. Spilcelets 2- to many-flowered, arranged in a lax or narrow panicle; rhachilla disarticulating above the 2 outer glumes and between the flowering glumes. Two outer glumes longer or shorter than the flowering glumes, somewhat rigid, empty, keeled, acute, awnless. Flowering glumes more or less imbricated, rounded on the back at the base, coriaceous or chartaceous, often hairy on the margins and callus, 3-nerved, 3-lobed or 3-toothed at the apex, the lobes equal or the central one produced into a short awn or mucro. Palea broad, thin, with 2 almost marginal keels. Lodicules 2. Stamens 3. Styles short, distinct; stigmas plumose. Grain usually compressed on the back, free within the flowering glume and palea.
Species from 25 to 30, mostly in the temperate regions of both hemispheres, a few in tropical America. The New Zealand species belong to the subgenus Rhombolytrum, characterized by the lateral teeth of the flowering glume being very small or almost obsolete, the middle tooth being also small and mucronate. It contains a few Chilian and North American species in addition to the three found in New Zealand, all of which are endemic.
| Densely matted; culms 1–3 in. Panicle often reduced to a single spikelet. Outer glumes ovate. Flowering glumes silky on the margins, distinctly 3-toothed at the apex | 1. T. exigua. |
| Culms tufted, 2–6 in. Panicle of 8–12 spikelets. Outer glumes lanceolate. Flowering glumes sparsely silky, 5–7-nerved, minutely 3-toothed at the apex | 2. T. pumila. |
| Culms tufted, 2–4 in. Panicle of 6–15 spikelets. Outer glumes broadly ovate. Flowering glumes glabrous, 9-nerved, obscurely 3-toothed or irregularly erose at the apex | 3. T. australis. |
1. T. exigua, T. Kirk in Trans. N.Z. Inst. xiv. (1882) 378.—Small, densely matted, forming a compact sward. Rhizomes long, creeping, branched. Culms erect from the rhizome, slender, wiry, glabrous, 1½–4 in. high. Lower leaves reduced to sheathing scales; upper shorter than the culms, ½–2 in. long, very narrow, convolute, filiform, rigid, erect or curved, acute or almost pungent at the tip, quite glabrous; sheaths closely appressed, pale, membranous, grooved; ligules reduced to a line of short stiff hairs. Panicle frequently reduced to a single spikelet, sometimes 2–3, rarely as many as 4–5; pedicels short, slender, minutely scaberulous. Spikelets about ⅕ in, long, ovoid-oblong, 2–4-flowered. Two outer glumes subequal, as long as the flowering glumes or very slightly shorter than them, concave, ovate, subacute, rigid, the lower one 5-nerved, the upper 7-nerved. Flowering glumes broadly ovate, silky on the margins and back towards the base, minutely scaberulous above, 9-nerved, shortly 3-toothed at the apex, the middle tooth mucroniform, not much longer than the lateral teeth. Palea broad, ciliate on the keels.—Danthonia pauciflora, Buch. N.Z. Grasses, t. 36b (not of R. Br.).
