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Group (a)
1. Th. venosa R. Br. Prodr., 1810, 314
A compound species of 4 closely related jordanons adapted for but not entirely confined to life in subalpine bogs. One jordanon is endemic in Australia, one endemic in New Zealand, and the other two occur in both countries.
Th. venosa var. typica Hh. n.nom.
Th. venosa R. Br. l.c. sens. strict. Cheeseman, Man. N.Z. Flor., 1925, 343. Hatch, Trans. R.S.N.Z., 76, 1946, 58 Macdonaldia venosa (R. Br.) Ldl. Swan River App., 1839, 50
Up to 80 cm. high. Leaf up to 40 cm. long, recurved, concave with exterior ridges, linear-acuminate. Flowers 1–12, purple with conspicuously darker striae, perianth segments up to 18 mm. long. Labellum broad at the apex and tending to be crenulate. Column inclined backwards, purplish at the base, with 0–3 broad blue vertical striae. Column-wings bright yellow. Midlobe absent, lateral lobes primary, erect, almost invariably entire, spirally involute and higher than the anther.
Distribution. Australia—not uncommon in high country bogs throughout Tasmania, South Australia, Victoria and New South Wales. New Zealand—3b. (Waikato) Rukuhia, Ohaupo, 12.1919, H. B. Matthews. 5. (Volcanic Plateau) Tirau, Rotorua, T. F. Cheeseman. Taupo, 12.1944, T. W. Mellor. 6. (Egmont-Wanganui) Ngaire, T. F. Cheeseman. 7. (Ruahine-Cook) Tararua Ranges, 12.1938, V. D. Zotov.
Flowers Dec.–Jan., 500–2,000 ft.; almost always confined to swamps and bogs; rather rare.
(b) Th. venosa var. cedricsmithii Hh. n.nom.
Th. uniflora Cheesemn. in part (not of Hook, f.)
Epiblema grandiflora Buch. Trans. N.Z. Inst., 14, 1882, 357 (not of R. Br.)
Up to 40 cm. high. Similar to but considerably smaller than var. typica, differing mainly in the simple labellum and in the lobes of the column-wing, which are shorter than the anther.
Distribution. Endemic—4. (East Cape), 5. (Volcanic Plateau), 6. (Egmont-Wanganui), 7. (Ruahine-Cook), 9. (North-eastern), 10. (North-western), 11. (Western), 12. (Eastern), 13. (North Otago), 14. (Fiord), 15. (South Otago). Montane and subalpine areas throughout.
Flowers Dec.–Jan., 2,000–4,000 ft.; abundant in bogs and along river banks, often extending to drier situations. Probably derived from var. typica. The illustration over the name Th. unifolia (Cheeseman, Illus. N.Z. Flora., 2, 1914, t193a) can be regarded as the hypo-type of the variety, which is gratefully dedicated to Mr. Cedric Smith, of Stewart Island, whose enthusiastic assistance has proved invaluable.
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(c) Th. venosa var. cyanea (Ldl.) Hh. n.comb.
Th. uniflora Hook. f. Flor. Ant., 1, 1844, 70, sens. strict.
Th. cyanea (Ldl.) Benth. Flor. Austr., 6, 1873, 323
Th. venosa Hook. f. Flor. Tasmn., 1, 1860, t102 (not of R. Br.)
Maodonaldi cyanea Ldl. Swan River App., 1839, 50
Refer also Hatch, Trans. R.S.N.Z., 76, 1946, 58
Up to 30 cm. high. Similar to var. cedricsmithii, differing in the narrower perianth segments and the recumbent, hardly involute, distinctly bifid lobes of the column-wing.
Distribution. Tasmania—occasional throughout. New Zealand— 2. (North Auckland) Kaikohe, Jan.–Feb., 1950, J. Jones. 16. (Stewart) Stewart Island, 1.1949–50, C. Smith. Auckland Islands, 2.1943–5, J. F. Findlay.
Flowers Jan.–Feb., sea-level–1,000 ft.; bogs and stream banks, often in grass.: Probably derived from var. typica. Hooker's illustration over the name Th. venosa (Flor. Tasmn., l.c.) can be regarded as the hypotype of the variety. (Refer also Bentham, Flor. Austr., l.c.)
When Hooker described Th. uniflora, he stressed the many similarities which that species shared with the Tasmanian Th. cyanea (Ldl.) Benth. Cheeseman (Manl. N.Z. Flor., 1906, 672) suggested that the two might even prove to be identical. Later, however (refer hypotype var. cedricsmithii), he illustrated a plant from Mt. Ruapehu which was quite unlike the Tasmanian species as described by Lindley and illustrated by Hooker. In 1945 the writer compared Ruapehu plants with sketches, photographs and dried specimens of cyanea and found them distinct. (Trans. R.S.N.Z., 76, 1946, 58.) In 1947 Smith suggested that the Stewart Island form of uniflora was in fact cyanea and sent living material to prove his point. These specimens not only agreed with cyanea exactly, but were quite unlike the plants from Ruapehu. It was then left to discover the true nature of the Auckland Island jordanon, which was the type of Hooker's uniflora. To this end the writer studied the orchid collections made in the Auckland and Campbell Islands by the Cape Expedition during 1943–5. All the specimens there labelled “uniflora” were in fact cyanea, and Hooker's name had perforce to give way to the earlier nomenclature of Lindley, leaving the Ruapehu jordanon without a name. Since the latter was undoubtedly distinct from cyanea, the name cedricsmithii was proposed. (Int. Rules Bot. Nom., Art. 56.) The earlier writers, following Lindley, had used the bifid tips of the column-wings, or their absence, as major specific characteristics. In 1949 the writer studied the development of the column-wings and found the bifid tips to be unstable. Jordanons given specific rank on that account were not really entitled to it and in the present paper are treated as varieties. In cyanea the tips are distinctly bifid in the bud, but one point grows faster than the other, causing the mature lobes to be irregularly bifid, or if the flower is not immediately pollinated, almost entirely acuminate. In cedrismithii and venosa the tips are only very slightly bifid in the bud, and by the same process of lopsided development, almost invariably acuminate at maturity.