[Read before the Otago Institute, 17th January, 1878.]
The isolated hill which guards the entrance to the Bluff Harbour has long been supposed to exhibit features of special interest to the botanist, but no one has even imagined that it possessed a rich or varied flora. It was therefore with no little surprise that I found it vying with the North Cape in botanical riches, which, although of a less showy character, were not less attractive.
My examination of the locality was restricted to some portion of the forest beyond the pilot station, and to parts of the hill within reach during a rambling ascent from the town to the flagstaff.
The Bluff Hill is a little under 900 feet in height, and rather less than two miles in diameter at its greatest width; its base is washed by the sea, except on the side which connects it with the promontory of which it forms the termination. It consists chiefly of syenite and clay-slates, the latter in many cases nearly vertical. The hollows and sides of the watercourses
on the exposed portion are occupied by patches of swamp, but much of the surface vegetation has been destroyed by repeated burnings, so that at first sight it appears about as unfavourable a locality for rare plants as could well be imagined.
Its southern face is covered with forest, bearing a general resemblance to the Seaward forest; but differing in the reduced proportion of matai and iron-wood, and in the diminished luxuriance caused by exposure, elevation, and soil.
The chief timber trees are the kamai (Weinmannia racemosa), rimu (Dacrydium cupressinum), miro (Podocarpus ferruginea), and iron-wood (Metrosideros lucida); of these the kamai is the most abundant; many specimens rival in size and luxuriance the finest to be seen in the Seaward forest, although in most cases they are of less dimensions.
A dense growth of Olearia nitida, Veronica elliptica, Aristotelia fruticosa and other shrubs is found at the sea margin, and gives shelter to a number of ferns and herbaceous plants, the most noteworthy of the former being Lomaria dura, which, like its near ally L. banksii, never grows far out of reach of the sea spray. On the outskirts of the forest the trees are much shorn and stunted by the wind: the largest trees occur in the hollows and sheltered places, still serviceable timber is found near the summit. Although the yield of timber per acre is very small when compared with the best parts of the sheltered forest on the downs, it would be more durable in quality.
A few cattle have access to the forest, but no great amount of injury has resulted from this cause at present. In all directions young trees were plentiful, from seedlings upwards, showing that a continuous process of renewal is taking place.
The underwood and the herbaceous vegetation exhibited the greatest luxuriance of growth; some of the leaves of the tataramoa (Rubus australis) were the largest I ever saw. Chiloglottis cornuta, an orchidaceous plant growing in several localities from Omaha to the Chatham and Auckland Islands, but remarkably local, exhibited a stout, robust habit quite new to me. Juncus nova-zelandica attains an extraordinary size, and exhibits a marked contrast to the ordinary specimens found on the open side of the hill. In sheltered places near the summit Cyathodes acerosa assumes a free growing luxuriant habit not frequent even in the north, and, with its profuse display of white and red fruit, presents a most attractive appearance. This remarkably luxuriant growth of the shrubby and herbaceous vegetation was evident wherever shelter could be obtained from the direct action of the wind, and must be chiefly attributed to the great amount of moisture constantly present in the atmosphere, and which is prevented from becoming injurious by the frequent high winds.
Ascending the hill direct from the town, but diverging widely from the beaten track, the first plant collected of special interest was Juncus lampro-carpus, a recent addition to our flora. Stunted specimens of Carpha alpina were observed at less than twenty yards above the sea-level. Gratiola nana occurred in several spots, and on swampy ground Drosera spathulata was abundant. On a patch of peaty soil at no great elevation the rarest of the New Zealand sun-dews, Drosera pygmœa, occurred sparingly. It is a minute plant, not more than half an inch across, and from its grey tinge may easily be passed over. It was originally discovered by Mr. Colenso at Cape Maria van Diemen nearly forty years ago, and hitherto has not been observed elsewhere in the colony, although in Tasmania and Australia it has a wide distribution in littoral situations. There can be no doubt that its minute size and insignificant appearance have caused it to be overlooked in New Zealand.
The alpine Carex cataractœ was observed at a low elevation associated with the white-flowered Mimulus radicans and small plants of Schœnus axillaris, not previously recorded from the South Island. Hydrocotyle muscosa and Eleocharis gracillima were found in swampy situations. Thelymitra uniflora waved its graceful purple flowers on peaty ground below the summit, sheltering its near ally Caladenia bifolia. Callixene parviflora with its attractive waxy flowers and fruit covered the surface, in some places intermixed with Herpolirion novœ-zelandiœ. A new species of Haloragis, recently described as H. uniflora, often formed a dense sward; the plant is readily distinguished from its allies by the solitary terminal flower. Marshy spots were occupied by Oreobolus pumilio with the characteristic mountain plant Cyathodes empetrifolia attaining great luxuriance on the drier ground.
Isolepis cartilaginea, a species of remarkably local distribution, occurred in one or two places, and a small species, doubtfully referred to I. fluitans for the present, was found in plashy spots near the summit.
The limited time at my command only allowed me to examine the restricted portions of the Bluff Hill already mentioned, but the results of my investigation warrant the inference that one-fourth of the entire phænogamic and fern flora of the colony may be collected here by a diligent investigator—an unusually high proportion to be found on such a small area and under many unfavourable conditions.
The adjacent Seaward forest is not nearly so rich in species as the Bluff Hill although its general growth is more luxuriant. This wealth of species in the latter locality must be attributed to the continuous supply of moisture present in an atmosphere frequently agitated by high winds and to the greater variety of soil and situation.
Only twenty-three species of naturalized plants were collected—a paucity which contrasts strongly with their abundance in the North Island. None of the species observed call for special remark.
The following are the most interesting of the indigenous species:—
Melicytus lanceolatus, Hook. f. Long supposed to be peculiar to the north, but is now found throughout the colony, although often local.
Drosera pygmœa, DC. A minute rosulate plant with numerous filiform one-flowered scapes, and a silvery cone in the centre, covering a hybernating bud. The cone is formed by the interlaced, laciniate, scarious stipules. The apparent distribution of this plant in New Zealand is most peculiar—a single habitat at the north-western extremity of the colony and another in the extreme south.
Haloragis uniflora, T. Kirk. On peaty ground below the summit.
Stylidium subulatum, Hook. f. Plentiful on peaty ground just below the summit: one or two plants were observed at less than twenty yards above sea-level.
Rumex neglectus, T. Kirk. Beyond the Pilot Station.
Caladenia bifolia, Hook. f. In the forest and on peaty ground near the summit; leaves varying greatly in size and shape.
Chiloglottis cornuta, Hook. f. Abundant in the forest and of large size.
Prasophyllum nudum, Hook. f. Open places near the summit.
Juncus lamprocarpus, Ehrh.
Isolepis cartilaginea, Br.
Lomaria dura, Moore.
Abundant in wooded rocky places by the sea.