Lepidothamnus, first described in 1860 by Rodolfo Amando Philippi (1808–1904), are commonly known as Southern Pygmy-pine. It is a genus of conifers belonging to the podocarp family Podocarpaceae. The genus includes three species of dioecious evergreen trees and shrubs, and creepers. L. intermedius and L. laxifolius are native to New Zealand. L. fonkii (the type species) is native to the Magellanic subpolar forests ecoregion of southern Argentina and Chile, where it grows as a low shrub or creeper in moorlands and bogs.
The genus (notwithstanding Philippi’s description of its South American member) was long included in Dacrydium, but in 1969, David de Laubenfels broke out the genus Falcatifolium and in 1982 C.J. Quinn 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.
This genus, which was submerged in Dacrydium by Bentham and Hooker (1880), is clearly distinct, consisting of three very closely related species, one endemic to southern Chile and the other two to New Zealand. Despite the marked geographical discontinuity, the 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 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. The genus appears relatively isolated in the family, although it may show a distant affinity with Lagarostrobos and Halocarpus, which are also devoid of axial xylem parenchyma and hypodermis and have no vascular fibres in the adult leaves.
Description. Lepidothamnus are trees, shrubs or creepers with narrow, linear spreading juvenile leaves giving way by gradual transition to strongly keeled, subulate, decurrent and appressed scales. Plants are dioecious or monoecious (C.J. Quinn; Taxonomy of Dacrydium Sol. ex Lamb. emend. de Laub. (Podocarpaceae); ©1982, Australian Journal of Botany vol.30, pages 311-320).
- Pollen cones appear solitary, terminal or axillary and have sessile attachment.
- Seed cones appear solitary and terminal, consisting of 3 to 5 bracts with very elongated bases, of which 1 or 2 are fertile. Each fertile bract bears an erect ovule within its axil that remains erect throughout its development and has a sharply reflexed micropyle.
- Seeds mature in the second year after after fertilization, are not compressed in shape, 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 become swollen, fleshy and pink to red at maturity.
Identification guide. The three species of Lepidothamnus may be distinguished through their growth habit, how tightly the adult scale leaves are pressed against the twigs, and whether the seed cones have a swollen podocarpium (James E. Eckenwalder; Conifers of the World: The Complete Reference; ©2009 Timber Press).
- L. fonkii is a dwarf shrub with tight adult scale leaves and an absent podocparium.
- L. intermedius is a small tree with adult scale leaves spreading away and an absent podocarpium.
- L. laxifolius is a dwarf- to miniature shrub with loose adult scale leaves and an present podocarpium.