It may look benign growing in your yard, but Sphaeropteris cooperi, the Australian Tree Fern, is a major invader in the forest. This is a popular ornamental because it so easy and fast to grow — and those are the exact same characteristics that enable it to take over aggressively in Hawaiian forests, out-competing the native hapu’u and choking out the understory plants.
Australian tree fern grows faster, photosynthesizes at a higher rate, has a higher leaf mass per area, and produces more fronds than the native Hawaiian hapu’u fern (Cibotium glaucum). The fern spreads by spores, which are produced abundantly and dispersed by wind and water. Its spores have been known to fly 7 miles from the parent plant!
Native to Queensland in northeastern Australia, the Australian Tree Fern has become a serious invasive pest on Kauaʻi, invading mesic and wet ‘ōhiʻa and koa forests including Kōkeʻe and the Lumahai and Hanalei valleys, where it achieves high densities and impacts native ferns through competition and displacement. Because it is popular with gardeners and widely available in nurseries, Australian Tree Fern unfortunately continues to spread to new areas.
This fern is on the Pono Blacklist — please do not plant it! Your Pono-endorsed landscaper or nursery professional can recommend native or non-invasive alternatives.