[Front Page] [Features] [Departments] [SGAP Home Page] [Subscribe]

Australian Plants online

Three (More) Rogue Aussies

Dan Austin

Editors' Note: The spread of Australia's Melaleuca quinquenervia (Broad-leaved Paperbark) in Florida's Everglades has been well documented. Less well known are some of the other Australian species causing problems in that State. This article looks at three of these "rogue" Aussies.

Acacia auriculiformis

Ear-leaf Acacia (Acacia auriculiformis) is just one of about 1200 species worldwide. A.auriculiformis is native to Australia where it has become adapted to disclimax habitats that are burned periodically. We have analogous habitats in southern Florida, and this is where ear-leaf acacia is escaping cultivation. The fruits (legumes) open to reveal chocolate-brown seeds with a contrasting yellow aril. This colour combination makes the seeds easy to see - several kinds of birds eat (and spread) the seeds.

A look at what birds have done to spread Brazilian pepper (Schinus terebinthifolius) should make anyone pause before concluding that Ear-leaf acacia is safe and will not follow suit. This, and other species of Acacia are notorious weeds. Parts of southern Africa are being overrun by Acacia. Africa's exotic invasion is leading to the demise of endemic and endangered members of the Proteaceae and many of the other 8500 native species (Eliot, 1995). Ear-leaf acacia is beginning to repeat this scenario in southern Florida.

Schefflera actinophylla

Schefflera actinophylla , the "Umbrella Tree", is widely used as an ornamental or indoor plant in temperate to tropical areas of Australia. The spikes of maroon flowers are frequented by both honey eating and seed eating birds. Select the thumbnail image or plant name for a higher resolution image (46k).

Schefflera (Schefflera actinophylla, formerly Brassaia actinophylla) is yet another Australian plant still cultivated for ornament. These plants were unknown in the wild in the late 1970s (Austin, 1979). The species first began to spread into the wild in south eastern Florida in the late 1980s. Fish crows, Mocking birds, Starlings, and probably other birds feed on the fruits. The story promises to be yet another repeat of the Brazilian pepper saga.

"In southern Queensland, the trees escaped cultivation and became pests in their own homeland!"

When I was in Queensland, Australia in 1989, I talked with Dr. Robert Johnson (Director of the Queensland Herbarium) about this species, sometimes called the Queensland umbrella tree. Johnson informed me that the species is native to northern Queensland, but years before had been introduced into southern Queensland. In southern Queensland, the trees escaped cultivation and became pests in their own homeland! The plants are tolerant of a wide range of habitats and soil conditions, and are distributed in Australia by birds (Brock, 1988).

Here in Florida, schefflera is invading scrub, a habitat that had been relatively immune to exotics. Not only is scrub endangered in southern Florida, it also contains many endemic native plant and animal species. As schefflera spreads, it crowds out native plants and replaces them with exotic, unusable plant tissues, actually poisonous tissues: they contain oxalic acid crystals, among others (Perkins, 1978).

Cupaniopsis anacardioides

The Australian carrotwood (Cupaniopsis anacardioides) is another tree that has been introduced and promoted for landscape use. In the summer, this species produces nickel-sized yellow capsules that bear black seeds with contrasting red arils partially surrounding them. The yellow-black-red combination is striking, and draws the attention of birds. In early summer field classes, my students and I watch Fish crows and Mockingbirds as they feast on the fruits in cultivated trees. We then walk to nearby habitats. In some areas, the carrotwood seedlings dominate the shrub layers of mangrove and hammock forest.

Lake Wyman Park in Boca Raton (Palm Beach County) and the Nature Conservancy Hammock north of Blowing Rocks Preserve (Martin County) are examples of invaded habitats on the east coast. On the west coast, Sarasota and Collier counties have reported more advanced stages of invasion.


  • Austin, D.F. 1978. Exotic plants and their effects on southeastern Florida. Environmental Conservation 5:25-32.
  • Brock, J. 1988. Top End Native Plants. Published by the author, Darwin.
  • Eliot, J.L. 1995. African plant kingdom besieged by invaders. National Geographic, Vol.188, No.2, p.136.
  • Perkins, K.D. and Payne,W.W. 1978. Guide to the poisonous and irritant plants of Florida. Institute of Food and Agricultural Sciences, Gainseville.

This article is reproduced with permission from the Summer 1996 issue of newsletter of the Florida Exotic Pest Plant Council.

Dr.Dan Austin is with the Department of Biology, Florida Atlantic University, Boca Raton, Florida.

[Front Page] [Features] [Departments] [SGAP Home Page] [Subscribe]

Australian Plants online - December 1996
The Society for Growing Australian Plants