Atherosperma moschatum Seeds | Southern Sassafras
LATIN NAME: Atherosperma moschatum
COMMON NAME: Southern Sassafras, Black Sassafras
Plant Profile
Atherosperma moschatum is an upright evergreen tree of the cool, wet forests of south-eastern Australia, reaching perhaps 30 metres in the deepest gullies, with a straight tapering trunk, pale grey bark and a narrow crown. It grows with myrtle beech and leatherwood on deep, humus-rich, acidic soils in humid air, and it regenerates in gaps and after fire.
The leaves are opposite, which is unusual in its forest, and they are 4 to 10 cm long, lance-shaped, glossy dark green above and paler beneath, toothed in the southern form and smooth in the northern one. Scattered through the leaf tissue, and concentrated just under the upper surface, are spherical ethereal oil cells, single cells packed with the aromatic oil that gives the crushed leaf its smell.
The species is dioecious, with male and female flowers on separate trees, and the flowers are simple: creamy white, a centimetre or so across, in small clusters in the leaf axils in spring, with an undifferentiated perianth rather than separate petals and sepals. Male flowers carry many stamens, female flowers a cluster of free carpels, and small insects visit them.
Pollination produces an aggregate of small dry fruits, each achene tipped with a long plumose awn, so the cluster looks like a tiny brush head. The awns catch the air and the fruits blow away one by one, which is how the tree colonises new ground. The generic name Atherosperma was given for exactly this feature: awn-seed.
Botanists spent a century arguing about where this tree belonged.
Science & Biotechnology
Atherosperma was originally placed in the Monimiaceae, the family of tropical shrubs with which it shares an undifferentiated perianth and opposite leaves. When DNA sequencing became routine, the southern temperate group turned out to be distinct from the tropical Monimiaceae proper, and it is now recognised as its own family, Atherospermataceae. The family is a textbook case of southern hemisphere distribution: Atherosperma, Daphnandra and Doryphora in Australia, Dryadodaphne reaching New Guinea, and Laurelia in both New Zealand and Chile.
The bark yields a volatile oil by steam distillation whose aroma is close to sassafras. The North American sassafras owes its smell to safrole, a phenylpropanoid withdrawn from food use after it proved carcinogenic in laboratory animals, and the caution built up around aromatic bark teas applies just as firmly here. Neither steam distillation nor extraction with supercritical carbon dioxide makes an unknown aromatic bark safe to drink.
Uses & Benefits
The tree has been used for a little of everything, and its best use now is the one with no history at all.
Bark from felled trees was brewed as a sassafras substitute in the early days of settlement in Tasmania and Victoria, and the wood was cut for sawlogs where the tree was large enough to satisfy a mill. Neither use lasted: the timber is pale, light and workable but not durable out of doors.
In cultivation it wants an acid, humus-rich soil that never dries out completely, shelter from wind and hot sun, and a cool root run. Hot, dry summers will finish it, so only a cool, humid district is worth trying.
Growing from Seed
It comes from a rainforest, it ripens in a wet season, and it behaves accordingly.
Sow the seed as soon as the fruits break from the tree, on the surface of a compost built from leaf mould, coarse sand and sieved acidic soil, and cover it with 3 mm of the same mix. Keep the tray cool, permanently moist and shaded; drying out at any stage is the usual reason for failure.
Prick the seedlings out as soon as the second true leaf has opened, into deep pots of the same acidic mix, handling them by the seed leaves. Keep the compost moist but never waterlogged, and pot on as the roots grow. Plant out at 30 to 40 cm in a sheltered spot with dappled light and a deep mulch, and protect the leader from slugs and possums until the tree is above browsing height.
Our Take
Southern sassafras is a tree for the gardener with a damp shaded slope and a taste for the unusual. If the theme appeals, plant the Chinese Sassafras tzumu in a warmer, sunnier bed for aromatic foliage in another genus, put a camphor tree where there is room for something large and evergreen, and finish the corner with a southern magnolia for summer flowers under the same canopy. Sow it fresh, keep it moist, shade it for its first years, and let it take its time.
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