Atherosperma is a monotypic genus of flowering plants in the family Atherospermataceae, order Laurales. It contains a single species, Atherosperma moschatum, known by several common names including black sassafras, Australian sassafras, southern sassafras, and Tasmanian sassafras.
The genus is endemic to south-eastern Australia, where it grows as a shrub or conical tree typically reaching 2 to 30 metres in height. Young branchlets, flowers, and the undersides of leaves are characteristically densely hairy. The leaves are lance-shaped to elliptic, 30-95 mm long, with a glossy green upper surface, and emit a nutmeg-like scent when crushed. Flowers are pleasantly perfumed, with white to cream tepals, often streaked with purple, appearing from July to October. The fruit is a densely hairy achene.
Two subspecies are currently recognised: A. moschatum subsp. moschatum, a small to medium tree with toothed leaf margins, and A. moschatum subsp. integrifolium, a slender shrub or small tree with mostly entire leaf margins, restricted to the Barrington Tops and Blue Mountains of New South Wales.
Within the family Atherospermataceae, the genus is most closely related to Nemuaron, a monotypic genus endemic to New Caledonia. The family also includes Doryphora sassafras (yellow sassafras), another Australian rainforest tree.
Etymology
The generic name Atherosperma derives from the Ancient Greek ather ("awn") and sperma ("seed"), referring to the conspicuous hairs on the fruit. The specific epithet moschatum is a Latin adjective meaning "musk-scented", alluding to the distinctive fragrance of the bark.
Distribution
Atherosperma moschatum is endemic to south-eastern Australia. It grows along streams in deep gullies at higher altitudes, occurring at Barrington Tops, the upper Blue Mountains, and Tia Gorge in New South Wales, as well as in cool-temperate rainforest across eastern Victoria and eastern Tasmania. It frequently co-occurs with Nothofagus cunninghamii and Elaeocarpus holopetalus. Subspecies integrifolium has a narrower range, confined to the Barrington Tops and Blue Mountains.
Ecology
Atherosperma moschatum grows in cool-temperate rainforest, typically along streams in sheltered deep gullies. Its smooth bark supports a rich lichen flora -- a field study in Errinundra National Park recorded 54 lichen species on these trees, with Pannaria microphyllizans the most commonly observed. These patches of cool-temperate rainforest are considered critical refuges for lichen populations in an otherwise fire-prone eucalyptus woodland landscape.
Taxonomy Notes
The genus was first formally described in 1806 by French naturalist Jacques Labiardiere in Novae Hollandiae Plantarum Specimen. A second species, Atherosperma integrifolium, was described by Edmond Tulasne in 1855, but was reduced to a subspecies of A. moschatum by Richard Schodde in the Flora of Australia (2007). That treatment -- recognising two subspecies -- is accepted by the Australian Plant Census and Plants of the World Online. Phylogenetically, the genus is most closely allied to Nemuaron, endemic to New Caledonia, placing both in the small Southern Hemisphere family Atherospermataceae within the order Laurales.
