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Volume 50, 1918
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Art. XIV.—Notes of a Botanical Excursion to Bunkers Island (Stewart Island).

[Read before the Otago Institute, 12th June, 1917; received by Editors, 22nd December, 1917; issued separately, 24th May, 1918.]

On the 7th April, 1917, in company with Mr. G. Biggar, of Croydon, I paid a visit to Bunkers, one of the group of islands off the north-east coast of Stewart Island. This scrap of land lies to the eastward of Herekopere, and is one of the Fancy Group. It is only about 700 metres long, with an average width of less than 100 metres. The highest point above sea-level is about 35 metres. The eastern end is a separate island at high tide, and in another part the island is almost cut in two by the action of the sea. The geological formation consists of rotten granite, a good deal of it being simply a sort of gritty clay. The sea has eaten into this soft material on the southern side, with the result that there are several slips and cliffs there, all of which show much recent denudation. Mr. C. Hansen, of Half-moon Bay, informs me that there is comparatively shallow water on the south and south-west of the island, which suggests that at no distant date the island was larger than at present.

Ecological Conditions.

In common with all other islands of the Stewart Group, Bunkers is subject to a high rainfall, with high winds, but a comparatively mild and equable temperature. On this island there is only a thin coating of peat. Probably it is on this account that there is but little evidence of bird traffic so far as the burrowing petrels are concerned, although penguins were not uncommon The edaphic conditions and the exposed situation combine to prevent any extent of forest vegetation, although there are not wanting signs of a onetime forest formation. Probably when the island was larger such a formation existed, but the present plant-covering might be called a “scrub” association.

Plant-Formations.

These may be divided under the heads of “scrub” and “rocks and cliffs,” but with a view to saving space I do not intend to do more than outline the associations.

The physiognomy of the scrub shows a smooth exterior, and has the usual grey-green colour of the Olearia-Senecio association of the Stewart Botanical District. Olearia angustifolia is the commonest plant near the sea, but Senecio rotundifolia and Veronica elliptica are common. Curious to relate, Olearia Colensoi, so common in similar associations on the islands in the vicinity, appears to be absent. Here and there Stilbocarpa Lyallii is seen in patches, and also the common coastal ferns Asplenium lucidum and

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A. obtusatum. Here and there are open patches covered with Hierochloe redolens mixed with Pteridium esculentum and Histiopteris incisa, and in other places with Arundo conspicua. On the higher portion of the island the principal “shrub” is Olearia arborescens, which grows to the dimensions of a small tree with a thick trunk and much-branched top. Great patches of Polypodium diversifolium are common under the scrub. The rock and cliff vegetation consists of the usual Poa Astom, Crassula moschata, Myosotis albida, Cyclophorus serpens, Tetragoma trigyna, and Apium prostratum. I do not propose to further describe in detail the plant-associations, but am appending a list of the plants noted, from which it will be seen that a somewhat varied type of plant finds a home on this isolated piece of soil.

Conclusion.

The list of species shows certain surprises. I saw no sign of Olearia Colensoi, so common on many other islands in this locality. Poa foliosa and Senecio Stewartiae, so plentiful on Herekopere, only about a mile distant, were also absent. On the other hand, the presence of Melicytus lanceolatus, Hemitelia Smithi, Weinmannia racemosa, and the orchids Earina mucronata and E. autumnalis suggest a former forest vegetation, of the destruction of part of which by fire there was some evidence. The total number of species listed is seventy, belonging to fifty-three genera and twenty-eight families. In addition to these, five introduced species were noted.

List of Plants Noted.

Pteridophyta.

Cyatheaceae.

  • Hemitelia Smithn (Hook. f.) Hook.

  • Alsophila Colensoi Hook f.

Polypodiaceae.

  • Polystichum vestitum (Forst. f.) Presl.

  • Asplenium obtusatum Forst, f.

  • —— scleroprium Homb. & Jacq.

  • —— lucidum Forst. f.

  • —— flaccidum Forst. f.

  • Blechnum capense (L.) Schlecht.

  • Histiopteris incisa (Thbg.) J. Sm.

  • Pteridium esculentum (Forst. f.) Cockayne.

  • Polypodium diversifolium Willd.

  • Cyclophorus serpens (Forst. f.) C. Chr.

Lycopodiaceae.

  • Lycopodium fastigitum R. Br.

  • —— volubile Forst. f.

  • —— Billardieri Spring.

Spermophyta.

Gramineae.

  • Hierochloe redolens (Forst. f.) R. Br.

  • Arundo conspicua Forst. f.

  • Poa Astoni Petrie.

  • —— caespitosa Forst. f.

  • —— imbecilla Forst. f.

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Cyperaceae.

  • Scirpus nodosus (R. Br.) Rottb.

  • Uncinia pedicellata Küken. (?).

Juncaceae.

  • Luzula campestris DC.

Liliaceae.

  • Astelia nervosa Banks & Sol.

  • Phormium Cookianum Le Jolis.

Orchidaceae.

  • Earina mucronata Lindl.

  • —— autumnalis (Forst. f.) Hook.

  • Thelymitra longifolia Forst.

  • Prasophyllum Colensoi Hook. f.

Polygonaceae.

  • Muehlenbeckia australis (Hook. f.) Meissn.

Aizoaceae.

  • Tetragonia trigyna Banks & Sol.

Cruciferae.

  • Cardamine heterophylla (Forst. f.) O. E. Schultz var.

Crassulaceae.

  • Crassula moschata Forst. f.

Cunoniaceae.

  • Weinmannia racemosa L. f.

Rosaceae.

  • Acaena Sanguisorbae Vahl. var. pusilla Bitter.

Geraniaceae.

  • Geranium microphyllum Hook. f.

Violaceae.

  • Melicytus lanceolatus Hook. f.

Thymelaeaceae.

  • Pimelea Lyallii Hook. f.

Onagraceae.

    • Epilobium pubens A. Rich.

    Halorrhagaceae.

    • Halorrhagis erecta (Murr.) Schindler.

    • Ghnnera albocarpa (T. Kirk) Cockayne.

    Araliaceae.

    • Stilbocarpa Lyallii J. B. Armstrong.

    • Nothopanax Colensoi (Hook. f.) Seem.

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    Umbelliferae.

    • Hydrocotyle novae-zealandiae DC.

    • Apium prostratum Labill.

    Cornaceae.

    • Griselinia littoralis Raoul.

    Myrsinaceae.

    • Rapanea Urvillei (A. DC.) Mez.

    Convolvulaceae.

    • Calystegia tuguriorum (Forst. f.) R. Br.

    Boraginaceae.

    • Myosotis albida (T. Kirk) Cheesem.

    Scrophularinaceae.

    • Veronica elliptica Forst. f.

    Rubiaceae.

    • Coprosma lucida Forst. f.

    • —— areolata Cheesem.

    • —— foetidissima Forst.

    • —— acerosa A. Cunn.

    • —— parviflora Hook. f.

    • Nertera dichondraefolia (A. Cunn.) Hook. f.

    • —— depressa Banks & Sol.

    Campanulaceae.

    • Wahlenbergia gracilis (Forst. f.) A. DC.

    Compositae.

    • Lagenophora pumila (Forst. f.) Cheesem.

    • Brachycome Thomsoni T. Kirk.

    • Olearia angustifolia Hook. f.

    • —— arborescens (Forst. f.) Cockayne and Laing.

    • Gnaphalium luteo-album L.

    • —— collinum Labill.

    • Helichrysum bellidioides (Forst. f.) Willd.

    • —— filicaule Hook. f.

    • Senecio lautus Forst. f.

    • —— rotundifolius Hook. f.

    • Sonchus littoralis (Kirk) Cockayne.

    Introduced Plants.

    • Holcus lanatus L.

    • Poa trivialis Lind. (?).

    • Stellaria media Vill.

    • Brassica oleracea L.

    • Hypochaeris radicata L.