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Manual of the New Zealand Flora.
21. Trisetum, Pers
21. Trisetum, Pers.
Perennial or rarely annual grasses. Leaves flat. Spikelets rather small, usually 2-flowered, more rarely 3–6-flowered, arranged in a narrow dense or lax panicle rhachilla disarticulating above the 2 outer glumes, more or less produced between the flowering glumes and beyond the upper flower into a short bristle. Two outer glumes persistent, empty, equal or unequal, acute, keeled, 1–3-nerved. Flowering glumes 2–3, rarely more, equalling or exceeding the empty glumes, membranous with broad hyaline margins, 2-toothed at the apex, the teeth often produced into bristles or short awns; dorsal awn from the back below the tip, slender, straight or bent, often twisted page 880at the base. Palea strongly 2-nerved, 2-toothed. Stamens 3. Styles very short, distinct; stigmas plumose. Grain enclosed within the flowering glume and palea, free.
A genus of about 60 species, most plentiful in the north temperate zone, but also found on the high mountains of the tropics and in South America and Australasia. One of the New Zealand species is widely spread, the rest are endemic.
* Awn at least as long as the glume, inserted on the back a little distance below the tip.
Glabrous or sparsely pubescent, 6–24 in. Panicle 2–10 in., rather lax. Empty glumes lanceolate, unequal 1, T. antarcticum. Pilose, 2–3 ft. Panicle 2–10 in., very slender. Empty glumes oblong or oblong-obovate, subequal 2. T. Youngii. Puberulous or tomentose, 2–12 in. Panicle dense, cylindric, ½–2 in. 3. T. subspicatum. **Awn very short, from between the terminal teeth of the glume.
Puberulous, 6–12 in. Panicle dense, cylmdnc, 1–3 in. Teeth of flowering glumes short 4. T. Cheesemanii.
| 1. | T. antarcticum, Trin. in Mém. Acad. Petersb. Sèr. vi. 1 (1831) 61.—Perennial, very variable in size and degree of robustness. Culms tufted, slender, smooth or sparsely pubescent, 6–24 in. high. Leaves usually shorter than the culms, narrow, 1/15–⅙ -in. broad, flat or involute, flaccid, smooth or the margins finely scaberulous; sheaths long, narrow, grooved; ligules short, truncate, hyaline, ciliolate. Panicle very variable, erect or inclined, contracted or rather lax, usually narrow, rarely broad and effuse, 1–10 in. long; branches short, slender, suberect, simple or again divided. Spikelets compressed, pale - green or brownish - green, shining, 2–3-flowered, rarely 1-flowered or 4-flowered, ⅕–¼- in. long. Two outer glumes unequal, the lower from less than ½ to ⅔ the length of the upper, lanceolate, acute, scabrid on the keel; margins broad, hyaline. Flowering glumes exceeding the empty glumes, oblong-lanceolate, 2-cuspidate at the apex, scabrous-pubescent on the back, margins hyaline; awn from the back a little distance from the tip, sometimes ¼-way down, not twisted, recurved, twice as long as the glume. Palea almost as long as the flowering glume. Rhachilla clothed with copious long silky hairs between the flowering glumes, produced beyond the upper flower into a silky bristle.—Hook. f. Fl. Nov. Zel. i.301, t. 68B; Handb. N.Z. Fl. 335; Buch. N.Z. Grasses, t. 39. Aira antarctica, Forst. Prodr. n. 41. Avena antarctica, Roem. and Schult. Syst. ii. 676; A. Rich. Fl. Nouv. Zel. 139; A. Cunn. Precur. n. 257 Raoul, Choix, 39. Danthonia pallida, A. Cunn. Precur. n. 256 (not of R. Br.).
Var. lasiorhachis, Hack. MSS.—Culms, leaf - sheaths, rhachis, and branches of the panicle densely pubescent. Other characters as in the type. North and South Islands, Stewart Island, Chatham Islands Abundant throughout. Sea-level to 4500 ft. page 881 |
| 2. | T. Youngii,Hook. f. Handb. N.Z. Fl. 335.—Culms tufted, slender, erect, pilose or glabrous, 1–3 ft. high. Leaves mostly at the base of the culms and much shorter than them, 1/12–¼ in. broad, flat, smooth, pilose with long soft hairs; sheaths grooved, glabrous or pilose; ligules short, truncate, lacerate, hyaline. Panicle slender, very narrow, 2–8 in. long; rhachis pilose branches short, close, suberect, few-flowered, also pilose. Spikelets compressed, pale-green or yellow-brown, shining, 1–3-flowered, about ⅕ in. long. Two outer glumes almost as long as the flowering glumes, subequal or the lower about ¼ shorter than the upper, oblong or oblong-obovate, suddenly acuminate, membranous, scabrid along the keel. Flowering glumes oblong-lanceolate, shortly 2-cuspidate, minutely rough on the back; awn from ⅕ to ¼ way down the back, rather stout, recurved, nearly as long again as the glume. Palea almost equalling the flowering glume. Rhachilla nearly glabrous, produced between the flowering glumes and above the upper flower.—Buch. N.Z. Grasses, t. 40B.
North Island Mount Hikurangi, Adams and Petrie!Tararua Range, Buchanan!South Island Not uncommon in subalpine localities, especially on the western side. 3000–5000 ft. Best distinguished from T. antarcticum by the much broader oblong or oblong-obovate empty glumes; but it is usually a taller and more pilose plant, with a narrower panicle. |
| 3. | T. subspicatum,Beauv. Agrost. 88.—Culms densely tufted, stout or slender, pubescent or tomentose, in New Zealand specimens from 2 to 12 in. high, rarely more. Leaves numerous at the base of the culms and much shorter than them, firm, erect, rather strict, flat, more or less downy or almost glabrous, 1/13–⅙ in. broad; sheaths rather lax, deeply grooved; ligules short, scarious, lacerate. Panicle short and dense, cylindric or almost ovoid, rarely slightly lobed or interrupted at the base, ½–2 in. long; rhachis densely tomentose; branches short, erect. Spikelets compressed, whitish or yellowish-green, rarely purplish, shining, 2–3-flowered, ⅙–¼ in. long. Two outer glumes unequal, lanceolate, keeled, scabrid along the keel, the outer 1-nerved, the 2nd 3-nerved. Flowering glumes oblong-lanceolate, 2-cuspidate or shortly 2-awned at the tip, hairy at the base, keel scabrid above, sides minutely rough; awn from ⅙ to ¼ way down the back, longer than the glume, straight or recurved. Palea about ⅕ shorter than the flowering glume, 2-nerved, scabrid along the nerves.—Hook. f. Fl. Antarct. i. 97; Handb. N.Z. Fl. 335 Benth. Fl. Austral. vii. 588 Buch. N.Z. Grasses, t. 40A.
South Island Not uncommon in alpine and subalpine localities throughout. Auckland Islands Kirk!Campbell Island Sir J. D. Hooker!Usually from 3500 to 5500 ft., but descends almost to sea-level in the Auckland Islands. A common alpine grass in most countries, extending into both arctic and antarctic regions. page 882 |
| 4. |
T. Cheesemanii,Hack, in Trans. N.Z. Inst. xxxv. (1903) 381.—Culms rather stout, erect, 3–12 in. high, naked and puberulous above, leafy below, 2-noded, the upper node in the lower ¼ of the culm. Leaves crowded at the base of the culms, flat, 1/10–⅛ in. broad, firm, erect, glaucous, finely scaberulous on the veins and margins; sheaths rather lax, subcompressed, minutely puberulous; ligules short, truncate, denticulate. Panicle very dense, cylindrical, 1–2⅓ in. long, ½ in. broad; rhachis tomentose; branches densely imbricate, short, binate or ternate. Spikelets elliptic-lanceolate, compressed, whitish-yellow, shining, 2-flowered, about ¼ in. long. Two outer glumes slightly unequal, lanceolate, acute, scabrid on the keel, minutely rough on the sides, the lower 1-nerved, the 2nd 3-nerved. Flowering glumes lanceolate, very shortly 2-cuspidate, slightly hairy at the base, minutely rough, faintly 5-nerved; awn very short indeed, from between the terminal teeth or just below them. Palea ¼ shorter than the glume, scabrid along the nerves. Rhachilla produced between the flowering glumes and beyond the upper flower, silky. North Island Mount Hikurangi, Petrie!South Island Canterbury—Craigieburn Mountains, Petrie! Cockayne!Hooker Glacier, T. F. C.Otago—Petrie! 3000–5000 ft. This has much of the habit and appearance of T. subspicatum, but differs from it, and from all the other species, in the very shortly bidentate flowering glume, with the intermediate awn springing almost from between the teeth, not from the back some distance below the teeth, as is usual in the genus. |