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Townsonia Cheesmn.
Description. A monotypic genus occurring in Tasmania and New Zealand. It appears to occupy the same position in relation to Acianthus as does Adenochilus to Caladenia. It probably originated in Tasmania as an offshoot of Acianthus and has been windborne to New Zealand. Another theory, originally propounded by Schlechter, suggests that Townsonia arose in the paleozelanic subantarctic areas and drifted northward along two routes into Tasmania and New Zealand. The description of the species is also that of the genus.
Townsonia viridis (Hook. f.) Schltr. Fedde. Repert., 9, 1911, 249.
T. deflexa Cheesmn., Manl. N.Z. Ft., 1906, 602.
Acianthus viridis Hook, f., Fl. Tasm., 2, 1860, 372.
Slender terrestrial herbs. Root of creeping, jointed, fleshy caudicles with small globular tubers arising from the joints. Leaves up to 8, independent of the flowering stem, arising from the caudicle on long petioles, ovate-orbicular, apiculate, repand. Flowering stem up to 18 cm. high. Stem bract rather high, foliaceous, sessile. Floral
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bracts sheathing, subacute. Flowers up to 4, superficially resembling Acianthus, small, green, erect in the bud, afterwards becoming horizontal and eventually deflexed. Dorsal sepal cumulate, broad, obtuse or subacute. Lateral sepals linear-lanceolate, obtuse, with inrolled margins. Petals minute, erect. Labellum clawed, shorter than the lateral sepals, ovate-concave, obtuse, the centre darker than the margins. Sensitive, normally lying along the lateral sepals, but on being touched springs up against the column, entirely covering it. Column shorter than the (erect) labellum. Column-wings broad, descending to the base. Stigma large, high on the column. Rostellum very small, between stigma and anther. Anther terminal, erect, 2–celled. Pollinia free, pollen granular.
Distribution. Australia—Tasmania, mountain gullies, very rare. New Zealand—10, Mounts Rochfort, Frederick and Paparoa, 11, 1904 et subseq., W. Townson; 14, Resolution Is. (Dusky Sound), W. A. Thomson; 16, Mount Anglem, 11, 1946, E. Willa.*
Sea-level-2,500 ft. Flowers Nov.-Dec., small groups in mossy scrub. It is worth noting that in the original Westport localities the plant was found growing in association with Olearia colensoi Hook. f. This same apparent partnership also occurs in Stewart Island. Nothing is known of the pollination of the species, but the mobile labellum suggests that insects may play a part. Smith's illustration (Cheeseman, Illus. N.Z. Fl., 2, 1914, t. 198b) may be regarded as the hypotype of the species.
[Footnote] * Since writing the above Townsonia has been discovered for the first time in the North Island. (5, Mt. Ruapehu—on the Ohakune Track—12, 1947, O. E. Gibson). Mr. Gibson sent living plants which compare exactly with the Stewart Island specimens illustrated here.