Lepidothamnus

Phil. (1861)

Common names

No common name.

Taxonomic notes

A genus of three species:

• L. fonkii (type species)
• L. intermedius
• L. laxifolius

The genus (nothwithstanding Philippi's description of its South American member) was long included in Dacrydium, but de Laubenfels (1969) segregated the genus Falcatifolium and Quinn (1982) further segregated the genera Halocarpus, Lagarostrobos, and Lepidothamnus, leaving Dacrydium sensu strictu, in its present form. These segregations were made on the basis of differences in female cone morphology, a criterion that has been used as the taxonomic basis for differentiating all genera in the Podocarpaceae (Quinn 1982) (although leaf morphology has since been found to also provide a consistent basis for taxonomic distinctions in Podocarpaceae; cf. Biffin et al. [2011]). Quinn also observes that "the [three] species are united by their distinctive cone morphology with its erect ovule, the absence of resin ducts in the leaves which occur universally elsewhere in the family [cit.] and a large number of cupressoid cross-field pits not found elsewhere in the family. Chemically, these species are also unique in the family, having cupressuflavone as their major biflavenoid constituent (Quinn and Gadek 1981)."

Molecular studies place Lepidothamnus sister to Phyllocladus within the Prumnopityoid clade of Podocarpaceae. The relationship is not very close, with a most recent common ancestor in Jurassic time, while the extant species have diverged during Tertiary (Paleogene into Neogene) time (Yang et al. 2022, Khan et al. 2023).

Description

"Trees, shrubs or creepers with narrow, linear spreading juvenile leaves giving way by gradual transition to strongly keeled, subulate, decurrent appressed scales. Plants dioecious or monoecious; male cones solitary, terminal or axillary; sessile. Female cones solitary and terminal, consisting of 3-5 bracts with very elongated bases, of which 1 or 2 are fertile. Each fertile bracts bearing within its axil an erect ovule" ... "that remains erect throughout its development" ... "and has a sharply reflexed micropyle. Seeds maturing in the second year, not compressed, becoming dark-brown to black and surrounded by an asymmetrical, membranous, basal sheath formed by the epimatium that is less than one-quarter the height of the seed. Bracts frequently becoming swollen, fleshy and pink to red at maturity" (Quinn 1982).

Distribution and Ecology

Chile and New Zealand (Quinn 1982) in mesic, lowland to subalpine vegetation associations. Like Pectinopitys, Podocarpus, Prumnopitys and Retrophyllum, the genus has representatives on both east and west sides of the Pacific Ocean. It thus predates the breakup of Gondwana, which happened in late Cretaceous time when South America separated from Antarctica.

Remarkable Specimens

The largest plants (though still not very big) are probably in L. intermedius, which also likely contains the oldest individuals.

Ethnobotany

Uses have been recorded only for L. intermedius.

Observations

See the species accounts.

Remarks

The genus name is from the Greek words for "scale" and "shrub". All members of the genus are small shrubs (one can be found as a small tree) with scale-like leaves.

Plants of this genus have been found in early Miocene (about 20 million years ago) sediments in southern New Zealand (Pole 2007).

Citations

Bentham, G. and J. D. Hooker. 1880. Coniferae, in Genera Plantarum (3)1:420-442. London. Available: Botanicus.org, accessed 2013.03.24.

Khan, R., R. S. Hill, J. Liu, and E. Biffin. 2023. Diversity, distribution, systematics and conservation status of Podocarpaceae. Plants 12:1171.

Philippi, R. A. 1861. Zwei neue Gattungen der Taxineen aus Chile. Linnea 30:730-735. Available: Botanicus.org, accessed 2013.03.24.

Quinn, C. J. and P. Gadek. 1981. Biflavones in Dacrydium sensu lato. Phytochemistry 20:677-681.

Yang, Y., D. K. Ferguson, B. Liu, K.-S. Mao, L.-M. Gao, S.-Z. Zhang, T. Wan, K. Rushforth, and Z.-X. Zhang. 2022. Recent advances on phylogenomics of gymnosperms and a new classification. Plant Diversity 44:340–350.

See also