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Key to N.Z. Species.
| Leaf cauline. cordate. Labellum ovate-acuminate, concave. Petals much shorter than the sepals | A. fornicatus |
| Leaf basal, oblong. Labellum linear-oblong, flat. Petals as long as the sepals | A. reniformis |
1. A. fornicatus R. Br. Prodr. 1810,321.
A compound species of 2 jordanons, 1 in Eastern Australia and 1 in New Zealand.
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1. Acianthus fornicatus var. sinclairii (Hook. f.) Hh., plant natural size. A.—Leaf reduced. B.—Flower from side. C.—Column and labellum from side (after Scammel). D.—Column from front (after Scammel). B-D.—Variously enlarged.
2. Acianthus reniformis var. oblongus (Hook. f.) R. and Hh., plant natural size. E.—Column from side. F.—Column from front. G, H.—Variations in leaf form (natural size). J.—Flower from side. K.—Labellum from above. E, F, J, and K.—Variously enlarged.
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A. fornicatus var. sinclairii (Hook. f.) Hh. Trans. R.S.N.Z., 75, 1945, 369.
A. sinclairii Hook. f. Fl. Nov. Zel., 1, 1853, 245.
Slender, up to 10 cm. high. Leaf more or less midway on the stem, sessile, cordate, acute or acuminate, silvery or reddish beneath, deeply bilobed at the base, entire or constricted. Floral bracts ovate-acute, often foliaceous. Flowers up to 15, usually 2–4. Dorsal sepal ovate-oblong, mucronate, cucullaté. Lateral sepals linear, muconate or acuminate. Petals much shorter, triangular. Labellum ovate-lanceolate, deflexed, concave, with 2 prominent basal calli and the distal portion studded with minute reddish papillae. Column short for the genus, unwinged, incurved. Pollinia deeply bilobed, 2 to each anther-cell.
Endemic—colonies in forest or scrub. Flowers June to August. Sea-level to 2,500 feet.
2, 3, 4, 5, 6, 7, Kermadec and Chatham Islands, abundant; 8, 10, occasional; 16, Pegasus; Wilson Bay, 7, 1946 (E. Willa); 7, 1945 (Mrs. Willa).
2. A reniformis (R. Br.) Schltr. Engl. Jahrb., 39, 1906, 39.
Cyrtostylis reniformis R. Br. Prodr., 1810, 322.
Caladenia reniformis (R. Br.) Reichb. f. Beitr. Syst. Pfl., 67.
A compound species of 3 jordanons, 1 recorded from all the Australian States, 1 confined to Victoria and South Australia, and 1 in New Zealand.
A. reniformis var. oblongus (Hook. f.) R. & Hh. Proc. Linn. Soc. N.S.W., 70, 1946, 59.
Cyrtostylis oblonga Hook. f. Fl. Nov. Zel., 1, 1853, 246.
C. oblonga var. rotundifolia (Hook. f.) Cheesmn. Manual N.Z. Fl., 1906, 685.
C. rotundifolia Hook. f. Fl. Nov. Zel., 1, 1853, 246.
C. macrophylla Hook. f. l.c.
Very slender, up to 6 cm. high. Leaf basal, sessile, oblong, orbicular-cordate, or reniform, obtuse or subacute. Floral bracts minute, ovate-acute. Flowers up to 5. Dorsal sepal linear, erect. Lateral sepals narrow-linear, spreading, acute. Petals similar. Labellum linear-oblong, obtuse or rarely emarginate, horizontal, or deflexed. Column slender, winged, incurved. Pollinia falcate, compressed, 2 to each anther-cell.
Endemic—small colonies in open mossy places in scrub or forest. Flowers July to October. Sea level to 2,500 feet.
2, 3, 4, 5, 6, 7 not uncommon; 8, 10, 12b, occasional.
The several variations described by Hooker as separate species have proved to be inconstant and due to epharmony. Cheeseman, dealing with the fertilisation of this species in 1874, suspected that this might be the case, and subsequently reduced Cyrtostylis rotundifolia to a variety of C. oblonga. Cheeseman's observations were confirmed in detail by the writer. It subsequently became apparent that if the South Australian form of Acianthus reniformis was only entitled to varietal rank, then the New Zealand plant could not well masquerade as a species. Rupp and the writer accordingly adjusted the nomenclature.