Ferns and Flowering-plants of Mayor Island, N.Z.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 56, 1926, Page 34

Ferns and Flowering-plants of Mayor Island, N.Z. By H. H. Allan and K. W. Dalrymple. [Read before the Philosophical Institute of Canterbury, 1st October, 1924; received by Editor, 24th October, 1924; issued separately, 6th March, 1926.] Plate 5. Mayor Island (Tahua of the Maori) lies in the Bay of Plenty, north-north-east of Tauranga, about 32 km. (20 miles) from the mainland and beyond the 180 m. (100fath.) depth line. The island, of volcanic origin, is somewhat square, of 1,277 ha. (3,154 ac.) extent, with a high ridge running east and west across the south end, and north and south on the western side, rising to about 396 m. (1,300 ft.) at the north end. The centre of the island is occupied by a great crater, some 8 km. (5 miles) in circumference, in which are two lakes—one of 2.5 ha. (6 ac.), dark blood-red from a distance; the other 8 ha. (20 ac.), of a deep blue-black. The colour is apparently due to the abundance of algal growth. There is a small opening, Opo Bay, on the south-east corner, the usual landing-place. Seaward there are rough water-worn cliffs streaked with veins of obsidian and surmounted by ash-beds sloping into the crater. Dr. L. Cockayne, F.R.S., has kindly forwarded us the notes taken by him on a very brief visit to the island in February, 1905, and the following account of the vegetation is based on these and upon the notes and specimens taken by one of us (K. W. D.) during a fortnight's stay in March, 1924. We have to thank Dr. Cockayne for critically examining certain of the specimens collected. The list of species shows that Mayor Island belongs to the Thames Subdistrict of the South Auckland Botanical District of Cockayne. * See Cockayne, L., 1921. Die Vegetation der Erde, xiv: The Vegetation of New Zealand, p. 300 et seq. Leipzig: Wilhelm Engelmann. The dominant tree is the pohutukawa (Metrosideros tomentosa), many specimens of which are of great size, the largest noted measuring 9 m. in circumference, with a trunk clear of branches for 3 m., and surmounted by a magnificent spreading head. The pohutukawa forms great groves in the lower flats all over the island. The slopes of the main ridges are a continuous succession of small, deep, dry gullies, the spurs of which are clothed in thickets of manuka (both Leptospermum scoparium and L. ericoides), amongst which Knightia excelsa, about 3.5 m. tall, is dotted about. The gully-bottoms have a dense growth of whau (Entelea arborescens), and the side-slopes contain large makomako (Aristoteha serrata) up to c. 0.7 m. in diameter, Litsaea calicaris, Dysoxylum spectabile, Suttonia australis, Brachyglottis repanda, Melicytus ramiflorus, and odd tree-ferns. The liane Rhipogonum scandens is frequent, and the undergrowth is mainly Coriaria sarmentosa, Rhabdothamnus Solandri, and a few ferns. The undergrowth is, however, much altered and depleted owing to the presence of pigs, while the unstable surface militates against regrowth. The high ridges contain a dense scrub in which manuka, Cyathodes acerosa vars., Leucopogon fasciculatus, Coprosma spp., Gaultherio oppositifolia are prominent.

There are small areas of swamp by the lakes, but otherwise the crater-basin is covered with pohutukawa and manuka. Much of the manuka shrubland is an indigenous-induced association on ground formerly cultivated by the Maori. In one place exists a clump of Pinus Pinaster, and this aggressive species threatens to extend its area rapidly. One old cultivation-ground is covered in Hibiscus trionum. A small grassy flat at Opo Bay, containing scattered pohutukawa, has as its main constituents Sporobolus indicus, Holcus lanatus, Dactylis glomerata, Poa pratensis, Lolium perenne, Trifolium repens, and is thus an exotic-induced association. There are a number of other exotic species established, especially on the old Maori clearings. Some of them are Ricinus sp., Rosa eglanteria, Phytolacca octandra, Oenothera odorata, Rumex obtusifolius, Solanum nigrum, Anagallis arvensis, Erigeron canadense. List of Species of Pteridophyta and Angiospermae. The list includes 98 species or distinct varieties, distributed among 78 genera and 50 families. The abbreviations “fl.” and “ft.” indicate that the species were observed to be in flower or in fruit in March, 1924. Lycopodiaceae: Lycopodium volubile Forst. f. Psilotaceae: Psilotum triquetrum Swartz. Marattiaceae: Marattia fraxinea Smith. Cyatheaceae: Cyathea dealbata Swartz; Cyathea medullaris Swartz; Cyathea Cunninghamii Hook. f. Polypodiaceae: Adiantum hispidulum Swartz; Cheilanthes Sieberi Kunze; Pteris comans Forst. f.; Pteridium esculentum (Forst. f.) Cockayne; Blechnum capense (L.) Schlecht.; Asplenium flaccidum Forst. f. Typhaceae: Typha angustifolia L. var. Gramineae: Paspalum scrobiculatum L. (ft.); Oplismenus undulatifolius Beauv. (ft.); Spinifex hirsutus Labill.; Dichelachne crinita (Forst. f.) Hook. f.; Dichelachne sciurea Hook. f.; Agrostis Billardieri R. Br. Cyperaceae: Mariscus ustulatus (A. Rich.) C. B. Clarke (ft.); Eleocharis sphacelata R. Br. (ft.); Scirpus nodosus Rottb.; Gahnia gahniae-formis (Gaud.) Heller; Uncinia sp. Liliaceae: Rhipogonum scandens Forst. (ft.); Cordyline australis Hook. f.; Astelia Banksii A. Cunn. (ft.); Astelia sp. (epiphytic); Dianella intermedia Endl.; Phormium tenax Forst. (ft.); Phormium Colensoi Hook. f. Piperaceae: Macropiper excelsum (Forst. f.) Miq. var. major Cheesem.; Peperomia Endlicheri Miq. (fl.). Proteaceae: Knightia excelsa R. Br. Polygonaceae: Muehlenbeckia complexa (A. Cunn.) Meissn. Chenopodiaceae: Salicornia australis Sol.; Salsola Kali L. Aizoaceae: Mesembryanthemum australe Sol. (fl.). Ranunculaceae: Ranunculus hirtus Banks et Sol. (ft.). Monimaceae: Hedycarya arborea Forst. (ft.). Lauraceae: Litsaea calicaris (Sol.) Benth. et Hook. f. (ft.). Cruciferae: Lepidium oleraceum Forst. f. var. Pittosporaceae: Pittosporum Colensoi Hook. f.; Pittosporum crassi-folium A. Cunn.; Pittosporum sp. (probably P. umbellatum).

Rosaceae: Acaena Sanguisorbae Vahl. var. (ft.). Oxalidaceae: Oxalis corniculata L. var. (fl.). Meliaceae: Dysoxylum spectabile (Forst. f.) Hook. f. (ft.). Euphorbiaceae: Euphorbia glauca Forst. f. Coriariaceae: Coriaria sarmentosa Forst. f. (ft.). Corynocarpaceae: Corynocarpus laevigata Forst. Sapindaceae: Dodonaea viscosa Jacq. Rhamnaceae: Pomaderris phylicaefolia Lodd. Elaeocarpaceae: Aristotelia serrata (Forst.) W. R. B. Oliver. Tiliaceae: Entelea arborescens R. Br. (ft.). Malvaceae: Hibiscus trionum L. (fl. and ft.). Violaceae: Melicytus ramiflorus Forst.; Hymenanthera novae-zelandiae (A. Cunn.) Hemsl. (ft.). Thymelaeaceae: Pimelea virgata Vahl.; Pimelea prostrata (Forst. f.) Willd. var. (fl.); Pimelea sp. (= P. Urvilleana Cheesem. non A. Rich.). Myrtaceae: Leptospermum scoparium Forst. (ft.); Leptospermum scoparium Forst. var. (ft.); Leptospermum ericoides A. Rich. (ft.) [there also occurs a form with narrow-linear leaves and small fruits that is possibly L. ericoides × lineatum]; Metrosideros tomentosa A. Rich. (ft.). Onagraceae: Epilobium cinereum A. Rich. Halorrhagidaceae: Halorrhagis erecta (Murr.) Schindl. (fl.); Halorrhagis procumbens (Sol.) Cheesem. Umbelliferae: Apium prostratum (DC.) Labill. (fl.). Araliaceae: Nothopanax Sinclairii (Hook. f.) Seem.; Nothopanax arboreum (Forst. f.) Seem. (ft.).; Nothopanax sp. ? [the specimens gathered include a single remarkable leaf of what may prove to be an undescribed species—there are seven sessile leaflets, the larger ones broadly obovate with tapering cuneate bases and rather distant blunt teeth: see Plate 5]; Pseudopanax Lessonii (A. Rich.) C. Koch. Ericaceae: Gaultheria antipoda Forst. f. var.; Gaultheria oppositifolia Hook. f. (ft.). Epacridaceae: Cyathodes acerosa R. Br. [there are distinct forms prescnt, one of which is probably var. oxycedrus (R. Br.)]; Leucopogon fasciculatus (Forst. f.) A. Rich. (ft.); Leucopogon Fraseri A. Cunn.; Dracophyllum Sinclairii Cheesem. Myrsinaceae: Suttonia australis A. Rich. (ft.). Loganiaceae: Geniostoma ligustrifolium A. Cunn. (ft.). Convolvulaceae: Calystegia Soldanella (L.) R. Br. (fl. and ft.); Dichondra repens Forst. Verbenaceae: Vitex lucens T. Kirk (ft.). Solanaceae: Solanum aviculare Forst. f. (fl. and ft.). Scrophulariaceae: Hebe salicifolia (Forst. f.) Pennell var. (fl.). Gesneriaceae: Rhabdothamnus Solandri A. Cunn. (fl.). Myoporaceae: Myoporum laetum Forst. f. (ft.). Rubiaceae: Coprosma grandifolia Hook. f. (ft.); Coprosma lucida Forst. f. (ft.); Coprosma lucida Forst. f. var. (ft.); Coprosma robusta Raoul (ft.); Coprosma robusta Raoul var. angustata Kirk ? [this is a very narrow-leaved form, and may be a hybrid; it does not belong to the × C. Cunninghamii group.) (ft.)]; Coprosma retusa Hook. f. Campanulaceae Lobelia anceps L. (ft.). Compositae: Brachyglottis repanda Forst.; Senecio Banksii Hook. f.

A leaf of Nothopanax sp. Mayor Island.