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Plates XVIII.—XX.
[Read before the Wellington Philosophical Society, 2nd February, 1877.]
Amongst the Protean plants of New Zealand few genera are in a more unsatisfactory condition than Dacrydium. The unisexual character of the species, the difficulty of procuring good flowering and fruiting specimens from the same individuals, and the local and difficult habitats of several forms, have led to great perplexity, through the combination of distinct species and a want of precision in the limitation of those admitted. It is hoped that the present paper will tend to remove these difficulties, although it must not be looked upon as final, since we may fairly expect that other species will yet be discovered in the mountain districts of the central portion of the North Island and the south-western portion of the South.
Although my attention has been specially directed to this genus for the last ten years, it was not until the commencement of last year that I was able to solve the difficulties by which it was surrounded, and to lay down more precise limitation for the recognized species with descriptions of others new to science. I am pleased to say that Sir Joseph Hooker and myself have independently arrived at the same conclusions, except with regard to a single species, and I take the opportunity of expressing my thanks to him for his valued notes, and for the opportunity so kindly afforded me of comparing several of the original specimens of Bidwill, Lyall, Colenso, and Hector, with my own collections.
The New Zealand species form two natural groups—the first distinguished by the young plants possessing terete spreading leaves which pass by very gradual transition, sometimes extending over a number of years, into the abbreviated and closely imbricated condition, characteristic of the mature state. With one exception all the species of this group are characterized by solitary fruit.
In the second group the young plants exhibit flat, linear, spreading leaves, which for the most part pass abruptly into the quadrifariously imbricated leaves characteristic of the fruiting state: leaves of an intermediate kind are
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rare, and when produced are merely the linear leaves diminished in size. In some specimens of D. kirkii there is reason to believe that this transition is not effected until the tree is thirty or forty years old. In D. bidwillii this change is effected by the end of the second or third year at most, although occasionally branches exhibiting the early form of leaf are produced on the trunk and primary limbs of old specimens. D. colensoi requires an intermediate period, and on old specimens of its most robust mountain form the early leaf state is rarely seen. The members of this group exhibit a strong tendency to produce aggregated fruit which attains its maximum in D. kirkii.
The species vary greatly in habit and dimensions. D. laxifolium is perhaps the most diminutive pine known; pigmy specimens may be covered by a crown-piece. D. bidwillii is a dwarf, often prostrate, shrub. D. cupressinum is commonly 80 feet high or more, with a trunk 2–4 feet in diameter, and weeping branches. D. colensoi is a small tree with short trunk and heavy round head. D. kirkii is a noble species, 60–80 feet high, with conical head and peculiar aspect from the lower spreading branches having leaves resembling those of a Picea, while the upper fastigiate branches have abbreviated cypress-like foliage.
Several species are of great importance from their economic value. D. cupressinum, the rimu or red pine, yields the greatest portion of the marketable timber produced in the South Island. It is of great value for all inside work, and is largely used for building purposes, but, although of great strength, is not durable when exposed. It is largely used in the manufacture of furniture. D. westlandicum, the Westland or white silver pine, is of great durability, probably owing to the large quantity of oily and resinous matter which it contains. It is exported from Westland to a considerable extent, and fetches a higher price in the Westland markets than any other timber except kauri. D. intermedium, the yellow silver pine, is considered still more durable, and is highly valued on the west coast of the South Island. D. colensoi, the yellow pine or tar-wood of the Otago settlers, is another species of great durability, although of rather small dimensions. D. kirkii, the manoao of the North Island, affords perhaps the most durable timber of all: small trunks the thickness of a man's arm, used as palisades in a Maori pa known to have been constructed ninety years ago, are said to be still perfectly sound and good. This species was sufficiently plentiful on the Great Barrier Island to admit of its conversion a few years ago, and the timber was placed in the Auckland market under the name of Barrier pine; but, owing to the removal of the machinery, the supply has ceased.