Another landscape tree native to Australia has not only escaped into the wild, but is invasive and becoming reproductive in Florida’s natural areas. This tree is carrotwood (Cupaniopsis anacardioides). It was first identified as a potentially invasive tree in 1989, about ten years after it became popular as a landscape tree. Since then, seedlings to medium-sized trees have established themselves outside of cultivation in disturbed sites and undisturbed natural areas. Carrotwood is found in habitats invaded by melaleuca and Australian pine, and has been compared to Brazilian pepper (Schinus terebinthifolius). Below are highlights of recent research that describes the extent to which carrotwood has invaded Florida
(Lockhart, et al., 1996).
Of greatest concern is the impact of carrotwood in mangrove communities. Mangroves are not highly competitive; carrotwood is. Many Florida industries depend on the animals that rely on the unique mangrove community. Carrotwood is already found in many counties where mangroves grow (compare Figures 1 and 2 on the back). A mangrove canopy opened by trimming or storms appears to be more prone to invasion. In addition, as urban sprawl continues and our native habitats diminish, all potentially negative impacts need to be examined and addressed.
- Carrotwood has escaped cultivation in 14 southern and central Florida counties.
- Habitats already invaded are: mangrove swamps, cypress swamps, beach dunes, coastal strand, coastal hardwood forests (hammocks), inland hammocks, slash pine flatwoods, sand pine scrub, and freshwater marshes.
- Forested habitats are more prone to invasion.
- Birds disperse the seeds, and contribute to a rapidly expanding wild carrotwood population, even on isolated islands.
- Wild trees are already reproductive in Brevard, Martin and Sarasota counties.
- Carrotwood densities are highest among the mangroves (to 24.16 plants per m2). Populations are also high in coastal hammocks (to 21.47 plants per m2).
- Carrotwood alters the natural species diversity of mangrove and coastal hammock communities.
- The time elapsed between plant introduction and escape into the wild was about 70 years for Brazilian pepper, 25 years for melaleuca, but only 10 to 25 years for carrotwood.
- Ordinances with varying degrees of restriction on carrotwood have been passed in the following counties: Dade, Sarasota, Lee, Pinellas, Charlotte, and Palm Beach, and in the city of Naples and the town of Sanibel.
We advise planting alternatives like pigeon plum, dahoon holly, inkwood, magnolias, laurel cherry, Jamaican dogwood, gumbo limbo, paradise tree, or mahogany. Trim fruiting branches to reduce the spread of carrotwood seed by birds. Chemical treatment before tree removal reduces root sprouts. Education for university and local horticulture staff, legislators, developers, nurserymen, homeowners, groundskeepers, etc., are essential now to reduce costly removal efforts in the near future.
Figure 2 Distribution of Mangrove Species in Florida
What can be done to avoid further impacts to natural resources, to dependent industries and their related costs?
Much is still unknown about carrotwood - its germination rate, its elevation limits, its success rate in the wild, its effects and rate of impact and displacement in native habitats. While understanding the nature of the beast can help us to deal with it, it is important not to wait for these answers to act upon the problem. We have learned from previous invasive exotic plants that playing catch-up is a costly game. It is time to take off the blinders and be pro-active.
- Education and active management of this exotic are the key to control:
Educate college and university horticultural staff and county extension staff to be cognizant of the problems already being caused by invasive plants, including carrotwood, and to warn about the dangers of their use.
Educate homeowners, developers, nurserymen and groundskeepers to help them to choose landscape plants more responsibly and better manage existing trees e.g., trim trees regularly each Spring before trees have mature fruit (and in preparation for hurricane season), OR replace the tree next Arbor Day.
Educate members of local, county and state governments to help them act more fiscally responsible to the taxpayers by taking early measures to control invasive exotics as they are identified.
- Heed the recommendations ("do not plant ") of the Florida Department of Agriculture, Division of Forestry (1993) which lists carrotwood as an invasive in their tree selection guide.
- Plant alternatives to carrotwood. Recommendations from the South Florida Water Management District and a Naples nurseryman include the following: paradise tree (Simarouba glauca), pigeon plum (Coccoloba diversifolia), inkwood (Exothea paniculata), gumbo limbo (Bursera simarouba), Jamaican dogwood (Piscidia piscipula), magnolias (Magnolia virginiana or M. grandiflora), loblolly bay (Gordonia lasianthus), mahogany (Swietenia mahogani), laurel cherry (Prunus caroliniana) and a relative of carrotwood which is native to the Florida Keys, Cupania glabra (A. Ferriter, W. Jones, personal communication, 1996).
- Stricter ordinances will reduce the availability of seed to birds who readily disperse it. Strong regulatory actions can minimize further expansion and moderate local populations.
- Control of carrotwood can be achieved in uplands by the use of a basal bark treatment with Garlon IV (E. Freeman, personal communication 1996). Information is not available for treatment in wetlands. Small trees can be girdled and sprayed with Roundup or Rodeo, but stump sprouts may need retreatment. Chemical treatment, however, should be used judiciously and as a last resort. Caution is indicated because of the sensitivity of mangroves to chemicals.
Lockhart, C., D. Austin, W. Jones, L. Downey. 1996. The Invasion of Carrotwood (Cupaniopsis anacardioides) in Natural Areas (in review). For a copy of the full report, contact Greg Jubinsky at or Chris Lockhart at
Last Updated: 09 September, 2010
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