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Range of the genus Dacrydium (de Laubenfels 1988).

 

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Dacrydium

Solander ex Lambert 1807, emend. de Laub. 1969

Common names

Taxonomic notes

A genus of 21 species:

Type species: Dacrydium cupressinum Sol. ex Lamb.

Quinn's 1982 revision of the genus concludes that "[a]s here emended, the genus Dacrydium is a highly uniform and natural taxon comprising 16 species (de Laubenfels 1969) ... Its closest affinity is with Falcatifolium, as evidenced by the presence of resin ducts and hypodermis in the adult leaves, axial parenchyma and taxodioid cross-field pits in the secondary xylem, and 10 metacentric chromosomes in all members of both genera examined." Moreover:

"Within the Podocarpaceae, genera have largely been recognized on character-states drawn from the morphology of the female cone... [Acmopyle, Saxegothea, Microcachrys, Microstrobos and Phyllocladus] are all relatively small genera in which many other characters of vegetative and reproductive morphology and anatomy have been found to be correlated with the differences in cone morphology, and so go to make up good sets of generic characters of more or less equal content.

"Although Podocarpus s.l. may have been a natural taxon, ... revision by de Laubenfels (1969) divided it into four genera, viz. [Dacrycarpus, Decussocarpus, Prumnopitys and Podocarpus], whose taxonomic content is more nearly equivalent to the preceding genera and to each other" (Quinn 1982).

Quinn (1982) applies similar reasoning to the large and heterogeneous genus Dacrydium s.l., accepting Florin's (1931) division of the genus into Sections A, B and C and de Laubenfels' (1969) segregation of Section A as Falcatifolium, retaining Section B as Dacrydium sensu strictu and segregating Section C into Lepidothamnus, Lagarostrobos and Halocarpus.

Description

"Trees or shrubs with spreading linear to subulate, sometimes falcate, juvenile leaves that normally give way to shorter, strongly keeled adult leaves in the form of either subulate decurrent needles often with incurved tips, or appressed scales. Plants dioecious; males cones solitary, sessile and terminal or axillary; female cones terminal, consisting of several leaf-like bracts of which only one is usually fertile. Fertile bracts bearing a single ovule in a medial position on the adaxial surface and inclined so that it is partially inverted when first formed. Seed maturing in one season, often slightly flattened and usually remaining distinctly inclined towards the cone axis. At maturity the epimatium forming a submembranous asymmetrical sheath around the base of the seed and less than one-third its height. Cone bracts sometimes becoming fleshy and brightly colored at maturity" (Quinn 1982).

Distribution and Ecology

"[E]xtending from New Zealand in the south through the islands of New Caledonia, Fiji, The Solomons, New Guinea and Indonesia to the Philippines, Thailand and southern China in the north" (Quinn 1982).

Big tree

Oldest

Dendrochronology

Ethnobotany

"Wood yellow or reddish in colour, sometimes handsomely figured, usually very resinous and durable. It is used for building purposes, furniture and other work" (Dallimore et al. 1967).

Observations

Remarks

"Dacrydium is derived from the Greek DAKRA, tear, referring to the resinous exudation from the wood" (Dallimore et al. 1967).

Citations

Florin, R. 1931. Untersuchungen zur Stammesgeschichte der Coniferales und Cordaitales. I. Morphologie und Epidermisstruktur der Assimilationsorgane bei den rezenten Koniferen. K. Svens. Vetenskapskad. Handl. 10(1).

See also

Van Royen 1979 provides extensive taxonomic citations.

Last Modified 2012-11-23