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Cyathea cooperi

Lacy tree fern, Australian tree fern

Family: Cyatheaceae

An arboreal fern, with large fronds, growing to potentially 12 metres (often seen smaller), with a trunk to 20 cm in diameter.

Records of this species span most of the NSW and Queensland coast. However, its natural distribution is somewhat confused as it has now rapidly colonised local bushland from gardens and landscapes, especially along nutrient enriched creeklines. However, there are records of collections in the 1800s from the central and south coast of NSW. It is now recognised as weedy in some areas. It stretches up to Cape York in Queensland. Victoria treat it as a weed where it occurs in the east of the state. It has become weedy in some other countries.

It can be found in warm temperate to tropical rainforest.

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 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. C. cooperi is quite distinctive from C. australis in that it has a more slender trunk with distinctive “coin spots” where old fronds have broken off the trunk and pale straw-like scales at the base of the fronds.

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.

In the garden

A very common fern in cultivation.

It grows best in high humidity and high soil moisture conditions, therefore use good quality mulches and top them up regularly to keep the soil moist and also provide nutrients to the shallow root system.

Grow it in a shady position with some protection from hot western sun for it to look its best. A great beautiful looking ornamental background or feature plant. It responds well to small amounts of organic fertiliser.

It adds structure to rainforest and shady gardens as well as water features and landscaped creeks.

Note: it can colonise creeklines very easily from wind-dispersed spores so please monitor for “fence-jumping” in this regard.

Propagation

By 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 cooperi cannot be treated in the same way and will not grow from sawn off sections and cannot be transplanted reliably.

Other information

This species is also known as Alsophila cooperi and Sphaeropteris cooperi.

This species is not typically subject to fire but can reshoot if fire is not too intense.

Cyathea – from the Ancient Greek ‘kyatheion’ – meaning “small cup” – referring to the compartment within the overall structure (sorus) that holds the spores.

cooperi – named by Ferdinand von Mueller in honour of Sir Daniel Cooper (1821-1902). Cooper was a Member of the old New South Wales Legislative Council from 1849 and of the new Legislative Assembly after responsible self-government was granted in 1856.

This species is not considered to be at risk of extinction in the wild.

NSW Flora Online (PlantNET) – Cyathea cooperi profile page          http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Cyathea~cooperi

Australian National Botanic Gardens – Cyathea cooperi profile page https://www.anbg.gov.au/gnp/interns-2003/cyathea-spp.html

Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.

By Jeff Howes. Editing and additional text by Dan Clarke