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Evergreen unisexual trees chiefly natives of Australasia, but occurring also in Chile, Borneo, and the Malay Peninsula; the genus includes altogether about twenty species. They are related to Podocarpus, which they resemble in producing the seed in a fleshy, cup-shaped receptacle. The leaves vary from scale-like ones (such as are common in the cypresses) on old trees to linear or awl-shaped ones on young trees.
A leading character of Dacrydium cupressinum, the type-species, and its immediate allies is that the mature seed is erect, and is free from the ‘epimatium’ (an outgrowth from the subtending fertile scale), which encloses it only at the base. However, this is not true of three other New Zealand species: D. bidwillii (mentioned in the main work), D. kirkii and D. biforme. In these the structure of the fruit is markedly different, for the seed is inverted and completely covered by the epimatium, as in Podocarpus. In Allan’s Flora of New Zealand, Vol. I, p. 104, it is suggested (and not for the first time) that these species should be transferred to Podocarpus. The objection to so doing is that they resemble other species of Dacrydium, and differ from Podocarpus, in what is the only constant character distinguishing these two genera, namely, that the seed-coat (integument) is free from the epimatium, while in Podocarpus it is completely concrescent with it. There are, of course, other characters by which the various sections of Podocarpus differ from Dacrydium, but this is the only one that holds good throughout. So it is not surprising that these anomalous species have been transferred to a separate new genus by C. J. Quinn, who names it Halocarpus (Austr. Journ. Bot., Vol. 30 (3), pp. 311-20 (1982)).
In the same paper Quinn transfers the Tasmanian Dacrydium franklinii to a new genus – Lagarostrobus – differing from the type species of Dacrydium and its nearer allies in the laxly arranged, spoon-shaped fertile bracts, separated from each by definite internodes. In this genus he also includes the New Zealand D. colensoi, which is not treated in this work.
Lastly, Quinn proposes the revival of the genus Lepidothamnus, which is founded on the Chilean conifer Dacrydium fonckii, and in this genus he also includes two New Zealand species. See further below, under D. laxifolium.