[Read before the Auckland Institute, 31st July, 1871.]
The Titirangi district may be defined as the tract of country bounded on the north by a line drawn from the head of the Waitemata to the mouth of the Muriwai River, on the west by the sea, and on the south and east by the
Manukau Harbour, the Whau portage and creek, and the Waitemata River. Its greatest length, from the Muriwai River to the North Head of the Manukau, is about twenty-two miles; the extreme breadth hardly fourteen. The area may be roughly estimated at 100,000 acres.
The eastern portion of the district is composed of low undulating clay hills, intersected with numerous gullies, and supports a somewhat scanty and very uniform vegetation. The hills are almost invariably covered with a stunted growth of Leptospermum scoparium, intermingled with patches of Pomaderris phylicifolia, and Pteris aquilina, with a more or less dense undergrowth of sedges. Occasionally Leucopogon fasciculatus, Dracophyllum Urvilleanum, and Epacris pauciflora appear; while amongst the whole are found a few herbaceous plants, as Geranium microphyllum, Acœna Sanguisorbœ Lagenophora Forsteri, Gnaphalium involucratum, a few grasses, and some naturalized plants. The banks of the smaller streams, and the bottoms of many of the valleys, are occupied with a close growth of various species of sedges and other uliginal plants. In these localities such forms as Cladium glomeratum, C. teretifolium, Eleocharis gracillima, Typha lalifolia, Drosera binata, Isachne australis, Gleichenia hecistophylla and Lycopodium laterale, are especially common.
The extensive mud-flats bordering the Whau and Waitemata Rivers afford a suitable habitat to the mangrove (Avicennia officinalis), which in many places forms large swamps. Nearer the shore, Juncus maritimus, Cladium junceum, Leptocarpus sim′plex, and Dichelachne stipoides, make a continuous fringe for miles; while among many other littoral plants, Ranunculus acaulis, Salicornia indica, Samolus littoralis, and Plagianthus divaricatus are most abundant.
There can be no doubt that the scanty flora and barren appearance of this portion of the Titirangi district is, in a great measure, owing to the pernicious practice of burning off the vegetation every summer. By the agency of fire the patches of bush found by the sides of the larger streams are yearly diminishing, while in the open country many plants, once probably not uncommon, have now become local, or almost extinct. Extensive areas have even become denuded of nearly all vegetation, except a dwarfed covering of Leptospermum, only a few inches high, with occasional patches of Schœnus tenax. As an illustration of the rapidity with which species are extirpated under a continuance of this practice, I may mention that I well remember seeing, four years ago, the hill sides yellow from the abundance of the blossoms of the kumarahou (Pomaderris elliptica), in a locality where now hardly a single plant can be found, and that only by the closest search.
The central part of the district, or what is generally known as the Titirangi Ranges, exhibits a very different vegetation to that just described, being entirely
covered with luxuriant forest. As to its physical features, it consists of two parallel chains of hills, trending nearly north and south, and separated by an intervening valley. The Nihotopu stream flows through the southern portion of this valley, discharging itself into the Manukau Harbour, while the northern part is occupied by the Waitakere River. Both these streams flow for a considerable distance at an altitude of 800 to 1,000 feet above the sea-level, and descend very abruptly towards the coast; in the case of the Waitakere, by a waterfall upwards of 200 feet high. The greatest elevation in the district, 1,500 feet, is attained by Te Anatuku mountain, immediately above the source of the Waitakere, but for several miles the range maintains an altitude of 1,100 to 1,300 feet.
The prevailing tree is the tawa (Nesodaphne Tawa), which probably forms three-fifths of the forest. Other common species are the hinau (Elœocarpus dentatus), rata (Metrosideros robusta), tangeao (Tetranthera calicaris), Myrsine Urvillei, Pittosporum tenuifolium, the rewa-rewa (Knightia, excelsa) kauri (Dammara australis), and rimu (Dacrydium cupressinum). The greatest altitude reached in the district is not sufficient to exercise any marked influence on the vegetation, a few species are, however, chiefly found on or towards the summit of the range, and among them the following are prominent—Pittosporum Kirkii, Drimys axillaris, Ixerba brexioides, Metrosideros lucida, Olea montana, and Dacrydium Colensoi. Generally speaking, the undergrowth is dense, and principally composed of various species of Gahnia and Astelia, supplejack (Rhipogonum scandens), Freycinetia Banksii, the arborescent ferns, several species of Coprosma, Senecio glastifolius, Myrtus bullata, and, above all, Alseuosmia macrophylla, which occurs in profusion from the sea-level to the crest of the hills. Ferns are abundant, especially in the deep and narrow gullies, where the Hymenophylleœ are particularly well represented, and often of most luxuriant growth, while in many places, although chiefly in the higher central valleys, the ground is carpeted with mosses and Hepaticœ, principally of the genera Hypnum, Isothecium, Hypopterygium, Plagiochila, and Gottschea.
The great abundance of kauri early attracted the notice of sawyers, and I am informed that the first saw-mill worked by machinery in this province was erected in the Titirangi district. After twenty-five years' sawing, few timber trees remain on the eastern side, but extensive forests, almost untouched, exist by the Waitakere River, and a considerable quantity is still to be seen between the Huia Bay and the Manukau Heads. Besides the kauri, the kahikatea (Podocarpus dacrydioides) and the rimu (Dacrydium cupressinum) are extensively sawn, as also in a smaller degree is the totara (Podocarpus Totara) and matai (P. spicata). The tanekaha (Phyllocladus trichomanoides) does not appear to have been cut for its timber, although it is both excellent and durable, while the kawaka (Libocedrus Doniana), and the
manoao (Dacrydium Colensoi) are too local to be ever of any use for economical purposes.
The western coast is extremely rugged and broken throughout its whole length, and presents a bold front to the sea, the cliffs generally being from 200 to 300 feet high, and in one locality at least, near the rocky islet of Parera, they attain a perpendicular height of over 500 feet. Near the Manukau Head, and extending about five miles northwards, a narrow belt of low sand hills may be seen on the seaward side of the cliffs, whilst further north the sea beats against the foot of a rocky coast line, except in a few isolated sandy bays.
The vegetation is principally composed of bush, but there is a considerable extent of open grassy land near the sea. In the forest the species appear to be nearly identical with those in the central part of the district, the principal difference being in the great abundance of Pittosporum ovatum, and the presence of Ozothamnus glomeratus, Myrtus Ralphii, and some others, together with the occurrence near the sea of Sapota costata. The sea cliffs and rocky slopes abound with interesting herbaceous plants, and would probably repay a more careful investigation than I have been able to give them. Among many other species, Celmisia longifolia, Angelica rosœfolia, Cotula, dioica, Spergularia rubra, Tetragonia trigyna, and Myosotis australis are abundant. On the sand dunes the common arenarian plants occur, while by the margins of the lagoons and at the mouths of the streams such forms as Triglochin triandrum, Crantzia lineata, and Myriophyllum pedunculatum are plentifully found.
Owing to the small area of land brought under cultivation, naturalized plants are not so common as in many other districts, and have exercised comparatively little influence on the indigenous vegetation. Still many species are found by road sides and near the sawing stations, and with the progress of settlement their numbers are yearly increasing. At present Hypochœris radicata is the species most generally diffused, unless Cyperus tenellus be considered of foreign origin. The various species of docks, Prunella vulgaris, Veronica serpyllifolia, Trifolium minus, Erigeron canadensis, together with the commoner pasture and forage plants, are also very generally distributed throughout the district.
The subjoined catalogues include about 460 phænogamic plants and ferns, together with nearly 110 naturalized plants. Although the number of indigenous plants noted is considerably larger than has hitherto been recorded from any district of like area, yet it will be materially increased when the central and western subdivisions have been more thoroughly examined.
Lepidium oleraceum, Forst. Two very distinct varieties are found in this district; one, which also appears to be the common form near Auckland, is a procumbent plant, with linear, deeply pinnatifid radical leaves, linear-
spathulate toothed cauline ones, small flowers and pods. The other is a stouter, erect plant, with oblong-spathulate simply serrate radical leaves, 2–4 inches long; cauline leaves obovate-cuneate, serrate at the tips; flowers and pods larger.
Viola filicaulis, Hook. f. This curious little plant is not uncommon by the side of streams, above 800 feet of elevation. I am not acquainted with a more northern habitat.
Melicytus macrophyllus, A. Cunn.? A handsome shrub or small tree, with large deep green leaves 5–9 inches long, and fascicles of rather large campanulate flowers, that are most abundantly produced; is common in many places, and is probably referable to a state of this species. It is, I think, the Melicytus, n. sp., mentioned by Mr. Kirk in the Trans. N.Z. Inst., Vol. I., p. 142.
Pittosporum ovatum, Kirk. A most abundant tree on the western coast, often forming a considerable proportion of the bush.
Pittosporum Kirkii, Hook. f. This fine species is also frequently met with on the higher portions of the ranges, generally epiphytic on Metrosideros robusta. Capsules often 3-valved.
Myriophyllum pedunculatum, Hook. f. Now recorded for the first time as an inhabitant of the North Island. It is of common occurrence on the western coast, generally fringing the brackish water lagoons.
Gunnera prorepens, Hook. f.? A stout, excessively branched, prostrate plant; is found on the west coast, often forming large matted patches in damp sandy places, and is doubtfully referred to this species until better specimens can be obtained. Peduncles very stout and fleshy, covered with numerous bright red pendulous drupes.
Myrtus pedunculata, Hook. f. Rare, and apparently confined to a single locality.
Apium leptophyllum, F. Muell. In February, 1871, I observed a solitary plant of this species near Henderson's Creek, probably accidentally introduced.
Loranthus, n. sp.? A very distinct looking species of this genus has been collected at an altitude of 1,400 feet; parasitic on Metrosideros robusta, but neither flowers nor fruit have been obtained. It is probably identical with Loranthus decussatus, described by Mr. Kirk in Trans. N.Z. Inst., Vol. III., p. 162.
Sapota costata, A.DC. Not uncommon near the Manukau Head. I am not aware that it has been previously found on the western coast of the island.
Myosotis australis, Br. Abundant on the cliffs of the western coast. A most handsome plant, covered, when in blossom, with racemes of large white flowers.
Myosotis Forsteri, Ram. and Sch. Very local, the most northern habitat known to me.
Veronica elongata, Benth. Also local, and apparently restricted to the vicinity of the Huia River.
Dacrydium Colensoi, Hook. Some confusion appears to exist about the variety of this species found in the Titirangi district, and also in several other localities. Dr. Hooker considers it to be the typical form of D. Colensoi, but I am informed that Parlatore, in his monograph of the Coniferœ, describes it as a new species, under the name of Dacrydium Kirkii.
Corsysanthes Cheesemanii, Hook. f. As yet I have only noted this in a single locality, but it is probably not uncommon, and overlooked from its small size. One of the earliest of our Orchids, generally seen in flower towards the close of May, and continuing in bloom until the commencement of August.
Chiloglottis cornuta, Hook. f. Local. This plant seems to differ from the C. cornuta of the “Handbook” in the more numerous glands on the lip, but is referred to that species by Dr. Hooker.
Gahnia, n. sp. Allied to G. setifolia, but differing in the smaller size, much more slender panicles, with much fewer shorter branches, and by the larger spikelets and nuts. Originally discovered by Mr. Kirk.
Gleichenia flabellata, Br. Only seen by the Nihotopu stream. I am not aware that it has been found further south.
Trichomanes strictum, Menz. Confined to the highest summits of the range, 1,200 to 1,500 feet.
Hymenophyllum, n. sp. Minute, forming patches on the trunks of trees. Rhizome long, wiry; fronds ⅙–1 inch high, simple, dichotomous, or sparingly irregularly digitately divided; segments linear-oblong, obtuse, with a stout costa and ciliate-toothed margins; involucres terminal, free, ovate; valves quite entire, not spinulose on the back. Easily distinguished from its nearest ally, H. minimum, by its smaller size, less divided, often quite simple fronds, and by the entire valves of the involucres.