Rough Tree-Fern

Alsophila australis

''Alsophila australis'', synonym ''Cyathea australis'', also known as the rough tree fern, is a species of tree fern native to southeastern Queensland, New South Wales and southern Victoria in Australia, as well as Tasmania and Norfolk Island.
Rough Tree Fern  Alsophila  australis,Alsophila australis,Australia,Geotagged,Spring

Appearance

The massive erect trunk is usually up to 12 m tall, although specimens reaching 20 m have been reported from Queensland, Australia. Fronds are bi- or tripinnate and may reach 4 m in length, occasionally even 6 m. These form a distinctive crown that is dark green above and lighter green below. It has quite adventitious roots, tubercles and hair-like follicles on its ‘trunk’.

Plants growing in southern Australia often lose their fronds by the end of winter, as is the case with ''Alsophila dregei'' in South Africa. Characteristically of this species, stipe bases are often retained around the trunk long after withering. They are covered with scales and conical, blunt spines towards the base. The scales range in colour from shiny brown to bicoloured and are often distinctly twisted. The sori are circular and occur on either side of the fertile pinnule midvein. True indusia are absent, although reduced scales may encircle the sori.

In its montane range, ''A. australis'' is ecologically important as it provides the nesting substrate for ''Exoneura robusta'', a native species of reed bee. These bees almost exclusively build their nests in the pith of dead ''A. australis'' fronds. This species of bee is an important pollinator of other plants in southeastern Australia, so thus it can be seen how ''A. australis'' is indirectly supportive of other plants in its ecosystem.

Naming

It was known by the aboriginal people of Illawarra as ''beeow-wang'', as ''pooeet'' at Corranderrk Station in Victoria, and as ''nanga-nanga'' in Queensland.

Cultural

In the horticultural trade, most plants labeled as ''Alsophila australis'' are in fact ''Sphaeropteris cooperi''. Much confusion has existed between the two, especially in the United States, despite the two species being quite distinct from one another. ''A. australis'' is relatively stout trunked and has a large number of closely spaced fronds emerging at one time, with a slower increase in trunk height. ''S. cooperi'' in contrast, grows more quickly with fewer fronds emerging each year and has a much narrower trunk, with the frond bases aligned vertically for some distance before arching outwards.

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Taxonomy
KingdomPlantae
DivisionPolypodiophyta
ClassPolypodiopsida
OrderCyatheales
FamilyCyatheaceae
GenusAlsophila
SpeciesA. australis
Photographed in
Australia