12.
Oreobolus, R. Br.
Dwarf perennial herbs, forming dense cushion-shaped masses in alpine bogs. Stems branched, very closely compacted, leafy throughout. Leaves numerous, close-set, distichous and equitant, more rarely irregularly imbricate all round. Peduncle axillary, short at first but lengthening after the flowers expand, strict, compressed, bearing a terminal spikelet with or without 1 or 2 lateral ones. Spikelets minute, narrow, 1-flowered; flower hermaphrodite. Glumes 3 or rarely 4, the outer the largest, the second and third subequal, the fourth when present small, not much longer than the nut. Hypogynous scales (perianth-segments) 6, in 2 series, subequal, narrow, rigid, erect. Stamens 3. Style slender, continuous with the ovary; branches 3. Nut obovoid, obtuse with a depressed star-like mark at the apex, smooth.
In addition to the 2 species described below, one of which extends to Victoria and Tasmania, there is also one in Andine and antarctic America, and another in the Sandwich Islands.
Leaves obscurely distichous. Peduncle shorter than the leaves; spikelets usually 2, rarely 1 or 3 |
1.
O. pumilio. |
Leaves conspicuously distichous. Peduncle often equalling or exceeding the leaves in fruit; spikelets usually 1 |
1
a.
O. pumilio var. pectinatus. |
Leaves obscurely distichous, very narrow, strict. Peduncle shorter than the leaves; spikelets usually 1 |
2.
O. strictus. |
1. |
O. pumilio,
R. Br. Prodr. 236.—Stems much branched, short, ½–2 in. high, forming broad and dense cushion-shaped masses. Leaves obscurely distichous, ½–1½ in. long, erect or incurved, rarely spreading, narrow-linear, narrowed towards the obtuse tip, concave or almost flat in front, veinless or indistinctly 3-nerved; margins minutely serrulate; sheaths equitant, membranous, 3-nerved. Peduncles stout, rigid, mostly shorter than the leaves; spikelets usually 2, rarely 3 or 1. Glumes 3–4; the outer one the largest, leaf-like, 3-nerved; the second and third about equal; the fourth, when present, minute, not much exceeding the nut. Hypogynous scales narrow-lanceolate, acute, serrulate. Stamens 3. Style-branches 3. Nut small, obovoid. obtuse, whitish or brownish.—
Hook. f. Handb. N.Z. Fl. 308;
Fl. Tasm. ii. 94;
Benth. Fl. Austral. vii. 346.
South Island: Nelson—Mount Rochfort and other mountains near Westpost,
Townson! Westland—Arthur's Pass,
T. F. C.; Kelly's Hill,
Petrie! Worsley's Pass,
Cockayne! Otago—Mountains above Lake Harris,
Kirk! 2000–4000 ft.
Var.
pectinatus,
C. B. Clarke, MS.—Larger and softer, sometimes forming tufts 3–5 ft. high and a foot or more in diam. Leaves conspicuously distichous, often almost flabellately arranged, with broad equitant 5–7-nerved membranous sheathing bases; lamina linear-subulate, rigid, channelled in front. Peduncles 1-flowered, often equalling or exceeding the leaves in fruit.—O. pectinatus,
Hook. f. Fl. Antarct.i. 87, t. 49;
Fl. Nov. Zel. i. 275.
North and South Islands, Stewart Island, Auckland and Campbell Islands: From the summit of Moehau (Cape Colville) and Taupo southwards, abundant in mountainous districts. Altitudinal range usually from 2000 to 4500 ft., but descending to sea-level in Stewart Island and the Auckland and Campbell Islands.
I have followed Mr. C. B. Clarke's views in the arrangement of the two forms of
O. pumilio described above. The typical variety is also found on the mountains of Victoria and Tasmania; var.
pectinatus is endemic. |
2. |
O. strictus,
Berggr. in Minneskr. Fisiog. Sallsk. Lund. (1877) 25, t. 6, f. 12–24.—Stems 2–3 in. high, creeping and rooting at the base, laxly tufted, much branched; branches not nearly so dense as in
O. pumilio, erect, curved, leafy throughout their length. Leaves obscurely distichous, 1–2½ in. long, strict and erect or secund, very narrow-linear, deeply canaliculate above, obtuse, margins minutely serrulate; sheaths broad, membranous, 3–5-nerved, rounded or truncate at the tip. Peduncle much shorter than the leaves; spikelets 1, rarely 2, narrow. Glumes 3; outer the largest, minutely serrulate; the two others subequal, narrow, erect. Hypogynous scales 6, narrow-lanceolate, acute, minutely serrulate. Stamens 3. Style-branches 3, long, filiform. Nut small, obovoid, narrowed at the base, obtuse, white.—O. serrulatus,
Col. in Trans. N.Z. Inst. xxii. (1890) 492.
North Island: Rangipo Plain, near Ruapehu,
H. Hill.
South Island: Nelson—Mount Arthur Plateau,
T. F. C.; Lake Rotoiti,
Kirk! Canterbury—Arthur's Pass,
Berggren! Kirk! T. F. C. Otago—Inch-
[
unclear: Glutha], Swampy Hill, Maungatua, Mount Kyeburn, Hector Mountains, Blue Mountains, Bluff,
Petrie!
Stewart Island:
Kirk! Usually between 2000 and 4000 ft., but descends to sea-level in Otago and Stewart Island.
Very close to
O. pumilio, but a much more laxly tufted plant, with narrower strict leaves, which considerably overtop the peduncle. |