Definition of Australian tree fern
: a fast-growing tree fern (Cyathea cooperi) native to Australia that has broad, finely-divided fronds and a thin stem and that is cultivated as an ornamental
- His black-bottom lagoon-style pool features two 20-feet-tall Australian tree ferns nearby.
- —Christine Cole, Orlando Sentinel, 2 Apr. 2004
- An avenue of Australian tree ferns spreads great green fronds to create a delicate pattern of light and dark over indigenous Irish ferns below.
- —Brian De Breffny, Architectural Digest, October 1986
