Libocedrus
Content
Description
Monoecious evergreen trees or shrubs.
Bark smooth but fissured, peeling in strips or flakes, fibrous, rich brown but weathering to blackish or gray.
Leaves in alternating whorls of 3 or 4 soon reduced to opposite decussate, those of the seedling single veined and linear, c. 1 cm long, changing abruptly on lateral branches and throughout mature trees to specialized scale forms.
Seed an elongated cone with two very unequal wings, a narrow wing along one side and an elongated more or less expanded wing at least twice as long as the seed on the other side and extending beyond and more or less outward from the seed apex (micropyle).
Distribution
Antarctic forests and tropical highlands present, Argentina present, Asia-Tropical: New Guinea present, New Caledonia present, New Guinea and nearby islands present, New Zealand present, S. Central Chile present
There are 7 spp. of Antarctic forests and tropical highlands including New Guinea, New Caledonia, New Zealand, and S. Central Chile with adjacent parts of Argentina. In Malesia: 1 sp. with 2 varieties endemic to New Guinea and nearby islands. .
Uses
The aromatic wood is similar to that of Juniperus in appearance and uses, with light coloured sap-wood and reddish brown to purplish heartwood. Where large enough it is much appreciated for construction and furniture while the bark is sometimes used for roofing.
Notes
The relationships of Libocedrus are emphatically with the Holarctic Thuja group of genera (Tju-joideae) within Cupressaceae making it phytogeographically much like the everywhere associated Nothofagus whose relatives are also in the north. Like the other members of Thujoideae, the leaves are strongly differentiated into lateral and facial types and even further like many of these genera the branches are also differentiated dorsiventrally (the Holarctic genus Calocedrus was for a long time included within Libocedrus). Attempts as in LI (1953) to attach Libocedrus to southern hemisphere cypresses (Callitroideae) by ignoring the highly specialized foliage forms and describing the seed cones as 'valvate' are inadmissible. The so-called valvate appearance is due to the few cone scales, the lowermost scales of any Cupressaceous seed cone being the same so that this appearance occurs wherever the number of scales is reduced, as in Chamaecyparis noot-katensis.
The species of New Guinea and of Chile have been placed into separate genera based on slight differences. The upper surface of the leaves of the Chilean species are so constricted that little or no space is left for stomata, making them more or less hypostomatic while other species are clearly amphistomatic but with rather few upper stomata. The New Guinea species was separated on the basis of spirally placed microsporophylls. In fact, simple opposite decussate pollen cones occur alongside crowded cones whose microsporophylls appear to be whorled or perhaps spirally placed. FLORIN & BOUTELJE (1954) carefully examined these cones and found each two decussate pairs of microsporophylls brought to the same level but certainly not spirally placed. On the other hand, they adduced some other minor distinctions for the New Guinea material, in particular that the stomate bands are more or less separated by narrow irregular stomate-free zones, a character not seen elsewhere in the genus. In my opinion these otherwise very similar species should not be separated generically by such unimportant distinctions.
The species of New Guinea and of Chile have been placed into separate genera based on slight differences. The upper surface of the leaves of the Chilean species are so constricted that little or no space is left for stomata, making them more or less hypostomatic while other species are clearly amphistomatic but with rather few upper stomata. The New Guinea species was separated on the basis of spirally placed microsporophylls. In fact, simple opposite decussate pollen cones occur alongside crowded cones whose microsporophylls appear to be whorled or perhaps spirally placed. FLORIN & BOUTELJE (1954) carefully examined these cones and found each two decussate pairs of microsporophylls brought to the same level but certainly not spirally placed. On the other hand, they adduced some other minor distinctions for the New Guinea material, in particular that the stomate bands are more or less separated by narrow irregular stomate-free zones, a character not seen elsewhere in the genus. In my opinion these otherwise very similar species should not be separated generically by such unimportant distinctions.
Citation
VAN ROYEN 1979 – In: Alp. Fl. New Guinea: 1
BOUTELJE 1954: p. 198. – In: Acta Horti Berg.: t. 4, pl. 7 & 8
SILBA 1986 – In: Phytologia Mem.: 108
DALLIMORE & JACKSON 1923: Handb. Conif.: 300
DE LAUB. 1972 – In: Fl. Nouv. Caléd. et Dép.: 145
LI 1953 – In: J. Arn. Arb.: 17
FLORIN & BOUTELJE 1954 – In: Acta Horti Berg.: 31
MASTERS 1895 – In: J. Linn. Soc. Bot.: 20
WARB. 1900 – In: Monsunia: 189
CARR. 1855: Traité Gén. Conif.: 84
FLORIN & BOUTELJE 1954 – In: Acta Horti Berg.: 31