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Cyathea australis is an arboreal tree-fern growing to potentially 20 m tall. It is known as the Rough Tree Fern due to the presence of shield-like plates (bases of old fronds), tubercles (knobbly bits) and masses of hair-like scales on its ‘trunk’.
It is found typically in rainforest as well as wet sclerophyll forest all along the NSW coast and tablelands, and into the western slopes, growing as far west as Warrumbungle National Park. It extends up the coast and tablelands into Queensland, growing in disjunct occurrences to around Rockhampton. It is common in Victoria, growing over most of the eastern half of the state as well as the southern half. There are very few records in South Australia but it is recorded from Mt Gambier area. It occus commonly in Tasmania as well as the islands of Bass Strait.
It prefers moist mountain areas and can grow on drier slopes compared to most other tree ferns.
Cyathea spp. generally produce large-compound fronds in a radiating formation. In this species, the radiating fronds are compound-pinnate, and may be up to 4.5 metres long by up to 2 metres wide, finely divided into pinnatifid segments with ultimate toothed to crenate segments at the end of the fronds on a stipe / petiole to 60 cm long. The base of fronds have shiny red hairs or scales to 5 cm long; a useful quick identification feature, generally light to mid-green in colour.
Being a fern, no spores are produced but rather spores are produced. In this species, spores are produced in sori (spores-houses) that are mostly circular, to 2 mm across, in rows on the underside of fronds.
A popular, cold-hardy tree-fern, adaptable to a variety of climates and soils. A great background or feature plant that is an extremely hardy.
They are even capable of tolerating direct sun when the roots are kept wet but may grow better in morning sun / afternoon shade environments. Responds well to fertiliser.
Grow in a well-drained soil with some reliable moisture.
Given the right conditions they can grow 100 cm or more a year.
They can be used as stand-alone taller plants to create an effect or focal point in a garden.
Plants grown in full sun can have their fronds burnt in very hot days.
From spores.
Large tree ferns are often sold by nurseries as trunks sawn off at the base. These are Dicksonia antarctica and they quickly form roots from the base when planted. Cyathea australis cannot be treated in the same way and will not grow from sawn-off sections and cannot be reliably transplanted.
Regenerates from spores after fire. Possibly old plants can reshoot if burnt.
In some parts of the world, this species is known as Alsophila australis.
Cyathea is a genus of around 600 species, distributed mostly over the tropical and sub-tropical regions of the world. There are 11 species in Australia. NSW currently has 4 species. Lord Howe Island has 5 species, 4 of which are endemic (with this profiled-species also occurring there).
Cyathea – from the Ancient Greek ‘kyatheion’ – meaning “small cup” – referring to the compartment within the overall structure (sorus) that holds the spores.
australis – Latin meaning ‘southern’ or ‘of the southern hemisphere’.
NSW Flora Online (PlantNET) – Cyathea australis profile page https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Cyathea~australis
VICFlora – Flora of Victoria Online – Cyathea australis profile page https://vicflora.rbg.vic.gov.au/flora/taxon/452c3d6a-a68b-47c1-9b88-f08060ab752b
Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.