The Epiphytic Orchids of New Zealand and a New Species of Pterostylis from Mount Egmont

Transactions and Proceedings of the Royal Society of New Zealand, Volume 78, 1950, Page 101

The Epiphytic Orchids of New Zealand and a New Species of Pterostylis from Mount Egmont By Edwin D. Hatch, Laingholm, Auckland, S.W.4 [Read before the Auckland Institute, December 15, 1948; received by the Editor, April 8, 1949; issued separately, February, 1950.] New Zealand's epiphytic orchids present few problems. They are at the southern limit of their distribution and consequently are small and but little varied. Dendrobium, Bulbophyllum, and Sarcochilus. are abundant in Australia, yet the New Zealand species have little affinity with any Australian forms. The trans-Tasman windborne movement which has so profoundly affected the distribution of some of the terrestrial genera seems to have had no effect on the epiphytes, and our species appear to have been derived from New Guinea forms, coming down by way of New Caledonia and Lord Howe Island. Generic descriptions have been purposely omitted from this paper in order to conserve space and avoid pointless repetition. 1. Dendrobium Sw. A very large genus with upwards of 1,000 species, many of which are now cultivated for their beautiful flowers. It extends from India to Japan, throughout the Malay Archipelago and New Guinea, to Australia, New Zealand and Polynesia; 600 species have been described from New Guinea alone, Australia has over 60, and New Zealand only 1. Dendrobium cunninghamii Ldl., Bot. Reg., sub. t. 1756 D. biflorum A. Rich., Flor. Nouv. Zel., 1832, 167, t. 26 (not of Swartz). D. lessonii Col., Trans. N.Z. Inst., 15, 1883, 326. Epiphytic on trees and rocks. Stems numerous, woody, jointed, erect or pendulous, much-branched, up to 120 cm. long. Leaves numerous, distichous alternate, up to 5 cm. long by 5 mm. broad, linear-lanceolate acute, coriaceous. Flowers 1–6 in lax racemes, white or pink, up to 2 cm. across. Sepals more or less similar, oblong acute. Petals similar, rather smaller. Labellum clawed, 3–lobed, the lateral lobes small, erect, brightly coloured pink or orange; the midlobe large, spreading, often decurved with undulate margins; lamina with several parallel calli. Column small, erect, with narrow wings extending above the anther. Stigma oblong, large. Anther terminal, opereulate. Pollinia 4, 2 to each anther-cell. Pollen waxy. Distribution. Endemic; not uncommon throughout the North, South and Stewart Islands. Flowers December-February, sea-level-2,000 ft. Related to and probably having a common origin with the Polynesian D. bilflorum Sw. 2. Earina Ldl. A genus of 10 species, 5 in New Caledonia, 2 in New Zealand and 1 each in Tahiti, Samoa and Fiji. It appears to have originated in New Caledonia and been windborne eastwards.

The writer cannot accept Cheeseman's E. aestivalis. The type locality, Muriwai, contains both robust and slender forms which flower in the spring or summer or both, or not at all. Material examined from localities as far apart as the Waitakeres, New Plymouth, Westland, and Stewart Island could not be distinguished from E. mucronata, although flowering at times ranging from December to May (all these plants were from coastal associations). During 1945–47 he had opportunity to observe 2 plants of E. mucronata which had been brought in from Hunua on their original Cyathea trunks and established in the fernery at the Auckland Winter Gardens. The first plant flowered in September, 1946, and again in February, 1947. This was not merely a drawn-out flowering period, but two distinct bursts of activity with a completely flowerless period of several months in between. The second plant flowered in September, 1945, and not again until February, 1947, a flowerless period of 17 months. It then flowered again in October, 1947. It is considered that E. aestivalis is nothing more than an epharmone of E. mucronata, brought about by the more rigorous conditions of the coastal environment. The floral morphology in both is identical and the slightly darker labellum in the summerflowering form is certainly not of itself sufficient to warrant retaining the species. Key to the Species Labellum sessile, bifid, without calli mucronata Labellum clawed, entire, with basal calli autumnalis (i) Earina mucronata Ldl., Bot. Reg., 1835, t. 1699. E. aestivalis Cheesmn., Trans. N.Z. Inst., 51, 1919, 93. E. quadrilobata Col., Trans. N.Z. Inst., 15, 1883, 325. Epiphytic on trees, ferns and rocks. Occasionally terrestrial, usually by the plant falling from above and seldom through germinating on the ground. Stems numerous, up to 90 cm. long, pendulous, slender, compressed, marked with black spots. Leaves 1–20, alternate, up to 15 cm. long by 4 mm. broad, linear acuminate, glabrous green, coriaceous. Flowers minute, creamy-white, 1–40 in a branched terminal panicle. Floral bracts minute, acute, finely striate. Sepals similar, spreading, the margins tending to infold. Petals rather broader, minutely crenulate. Labellum pale orange to almost red, sessile, without calli, 3–lobed, the midlobe bifid and abruptly deflexed. Column minute, erect. Stigma broad, high beneath the anther. Rostellum between the bases of the anther-cells. Anther terminal, 2–celled, fringed by minute column-wings. Pollinia 4, with or without caudicles, 2 to each anther-cell. Pollen waxy. Distribution. Endemic; common throughout the North and South Islands, extending to Stewart and the Chatham Islands. Flowers mainly September-November, with occasional robust coastal epharmones flowering between December and May, sea-level-2,000 ft. (ii) Earina autumnalis (Forst. f.) Hook, f., Flor. Nov. Zel., 1, 1853, 239. E. suaveolens Ldl., Bot. Reg., 1843, 61. E. alba Col., Trans. N.Z. Inst., 18, 1886, 207. Cymbidium autumnale Sw., Nor. Act. Upsal., 6, 1799, 72. Epidendrum autumnale Forst. f., Prodr., 1786, n. 319.

Epiphytic on trees and rocks. Stems numerous, pendulous, the panicle usually turning to become erect. Leaves 1–10, suberect, curved, linear acuminate, up to 8 cm. long by 8 mm. broad. Flowers 1–40 in a dense terminal, hardly branched panicle. Floral bracts minute, sheathing, deciduous. Flowers pale greenish-white, with irregular black markings. Sepals similar, ovate-obtuse. Petals rather broader, minutely crenulate. Labellum white, oblong, clawed at the base, minutely crenulate also. Lamina with 2 erect basal calli and 2 variously merging, central yellow splashes. Column erect with a conspicuous basal swelling. Anther terminal, 2–celled. Pollinia attached at the base by a caudicle to the prominent orange rostellum. Distribution. Endemic: common throughout the North, South and Stewart Islands. Flowers March-June, sea-level-2,000 ft. 3. Bulbophyllum Thouars Probably the largest orchid genus known, some 1,500 species having been recorded, mainly from tropical Asia, but extending to Africa, South America and Australasia. Over 500 species are to be found in New Guinea, 14 in Australia and 2 in New Zealand. Key to the Species Peduncles long. 2–4–flowered, labellum orange tuberculatum Peduncles Short, Flowers Solitary, Labellum White pygmaeum (i) Bulbophyllum tuberculatum Col., Trans. N.Z. Inst., 16, 1884, 336; 22, 1890, 488. B. exiguum Buch., Trans. N.Z. Inst., 16, 1884, 397 (not of F. v. M.). Dense masses on the trunks and branches of trees. Stems creeping, bracteate, bearing oblong-orbicular pseudobulbs in the axils of the bracts. Leaves solitary on the pseudobulbs, up to 3 cm. long by 5 mm. broad, oblong acute, coriaceous. Flowers white, 2–4 on long slender peduncles arising from the base of the pseudobulb. Dorsal sepal oblong, acute. Lateral triangular, acute. Petals similar to the lateral sepals, rather smaller. Labellum sensitive, orange, clawed, oblongovate, acute, fleshy and concave, the lamina with 2 small linear calli. Column short, erect, produced at the base, 2–winged above. Anther terminal, operculate, 2–celled. Pollinia 2–4, free. Distribution. Lord Howe Island, rare. New Zealand: not uncommon formerly throughout the North Island, but rapidly becoming rare. 10, Collingwood, Dall. Flowers April-May. sea-level-2,000 ft. Smith's illustration (Cheeseman, Illus. N.Z. Flor., 2, 1914, t. 191) can be regarded as the hypotype of the species. It must be noted, however, that the dissections in Smith's plate show the concave undersurface of the labellum and are not a typical view. (ii) Bulbophyllum pygmaeum (Smith) Ldl., Gen. et Spec. Orch., 1830, 58. B. ichthyostum Col.. Trans. N.Z. Inst., 26, 1894, 319. Dendrobium pygmaeum Smith, Rees Cyclop., 11, 1802, n. 27. Similar to but very much smaller than tuberculatum. Peduncles very short, flowers minute, solitary, greenish-white, minutely echinulate. Labellum spreading, incurved at the edges. Column with a prominent basal swelling.

Distribution. Endemic; fairly common throughout the North and South Islands. Stewart Island; East Ruggedy and Mason's Bay, 2.1949, S. Traill. Flowers November-February, sea-level-1,500 ft. 4. Sarcochilus R. Br. A genus of over 50 species, extending from India through Malaya to Australia, New Zealand, and Polynesia. Australia has 14 species, New Zealand only 1. Sarcochilus adversus Hook, f., Flor. Nov. Zel., 1, 1853, 241. S. breviscapa Col., Trans. N.Z. Inst., 14, 1882, 332. Epiphytic, usually confined to the upper branches of forest trees. Leaves 1–8, glabrous, coriaceous, up to 7 cm. long by 2 cm. broad, oblong ovate, acute or apiculate. Flowers 1–20 in a dense raceme rising from the axils of the lower leaves. As many as 5 peduncles are borne at a time. Stem and floral bracts minute, acuminate. Flowers minute, greenish-white, spotted with red. Sepals and petals more or less similar, the latter rather smaller, oblong acute. Labellum minute, coloured in a manner similar to the sepals, cup-shaped with 2 prominent greenish ealli near the tip. Column very small, rostellum prominent. Anther terminal, 2-celled. Column-wings dark purple, extending behind but not above the anther, and with acuminate lateral lobes forming a cavity over the stigma. Pollinia 4, 2 to each anthercell, attached to the rostellum by a caudicle. Pollen waxy. Distribution. Endemic. Not uncommon throughout the North and South Islands, and extending to Stewart and the Chatham Islands. Flowers October-November, sea-level-1,000 ft. Pterostylis irsoniana Hh. n.sp. Pt. montana typica et venosa affinis, probabilis hybridae originis. Map showing distribution of Pt. irsoniana Hh. Crosses mark the approximate spots where the colonies occur.

Demlrobium cunninghamii: (a) leaf: (b) Flower from front; (c) labellum from front; (d) column and labellum from side; (e) column from side; (f) column from front; (g) showing typical form of bud. Sarcochilus adversus: (h) plant natural size; (j) flower from front; (k) labellum from front (l) column from front; (m) column from side.

Eirina mucronata: (a) raceme natural size; (b) flower from front; (e) flower from side; (d) labellum from above; (e) column from front; (f) column from side.

Earina autumnalis: (a) raceme natural size; (b) flower from half front; (e) labellum from above; (d) column from front; (e) column from side.

Bulbophyllum tubcrculatum: (a) plant reduced: (b) flower from side; (e) labellum from front: (d) column from side. Figs. a–d copied from the hypotype; after Smith. Bulbophyllum pygmaenm: (e) leaf. pedunele, and flower. greatly enlarged; (f) plant natural size: (g) leaf and psendobulb; (h) labellum from side, showing elaw; (j) column from side.

Pterostylis irsoniana: (a) plant natural size; (b) column and labellum from side; (c) labellum from above; (d) tip of labellum; (e) lateral sepals; (f) stigma; (g) juvenile.

Folia montana similis, flos trullifolia alobula subsimilis. Sepalum dorsale caudatum, apex horizontalis aut incurvis. Sepala lateralia acuminata aut subulata, unum levis galea excedere. Labellum angustia gradatim ad apex levis turgidis, vel crenulata vel truncata. Basis labellum cum callo magno in genus singularis. Columna venosae typicae. Up to 17 cm. high. Leaves 1–6, narrow- to broad-linear, acuminate, flat or repand, up to 8 cm. long by 12 mm. broad. Flower solitary, up to 16 mm. high, translucent, with green and red striae. Dorsal sepal shortly caudate, the tip incurved or horizontal. Lateral sepals with an acute sinus, the lobes acuminate or subulate, only slightly exceeding the galea. Petals rather broad, falcate, acute, shorter or longer than the dorsal sepal, the upper half conspicuously red. Labellum gradually narrowed to a slightly swollen, truncate or variously crenulate tip; more or less translucent with the raised midrib and the swollen tip a dark red. Base of the labellum with a large dark prominent callus which is unique in the genus so far as the writer is aware. Column typical of Pt. venosa. Pt. irsoniana appears to have originated as a hybrid between Pt. montana typica Hh. and Pt. venosa Col. In its present state, however, it is obviously a true species, occurring over a wide area and breeding true to type. It produces ripe seed capsules, and undoubted seed-born juveniles of the montana type. Although the leaves vary considerably, the flower form remains constant. The general habit resembles that of montana. The flower is similar to trullifolia alobula except that the lateral sepals are usually acuminate as in montana. The column and labellum are those of venosa except that the latter has the swollen tip which is characteristic of trullifolia alobula. The basal callus cannot be likened to any known species of Pterostylis. This reversion to trullifolia is but further proof of the writer's contention that venosa has descended from the obtusa complex (Hatch, Trans. Roy. Soc. N.Z., 77, 1948, 243–4). In naming it, he has endeavoured to acknowledge the labours and enthusiasm of Messrs. J. B. Irwin and O. E. Gibson, who between them have done much to elucidate the orchid flora of Mount Egmont. Distribution. Endemic; 6, Mount Egmont, 12.1947–8, O. E. Gibson, J. B. Irwin. Flowers December–January, 3,000–4,000 ft. Locally abundant along grass tracks and roadsides and in scrub, in 6 or 7 localities on the northern and eastern slopes of Mount Egmont. Holotype in Herb. Hatch. No. 568, North Egmont Hostel, 3,800 ft. 12.1948, O. E. Gibson. The accompanying illustration can be regarded as the hypotype of the species. Mr. Gibson has had this plant under cultivation at New Plymouth since 1947, and reports that lowland conditions do not seem to affect the flower form at all, but that the leaves tend to be rather larger and the plant flowers a month earlier. Except for Bulbophyllum tuberculatum, which was drawn up from the hypotype, the descriptions and illustrations in this paper have been prepared from living material examined by the writer.