The Christmasberry, brought to the US from Brazil over a century ago, is notorious in Florida, Arizona, California and Hawaii for forming dense thickets of tangled woody stems that completely displace native plants and animals. In Florida, in particular, it has invaded approximately 700,000 acres of land, and is now recognised as the Everglade’s most serious alien plant threat, invading 10% of the park, mostly in pinelands and mangrove swamps.

“Christmasberry (Schinus terebinthifolius) is in the same plant family as poison Ivy and poison oak,” said Bill Gregg, an invasive species coordinator for the US Geological Survey (USGS). “It produces chemicals in its leaves, flowers and fruit that irritrate skin and respiratory passages of susceptible, often unsuspecting people.”

According to the USGS, the problem of invasive species is growing rapidly, as increasing numbers of the world’s plant species are brought into cultivation. Like the Christmasberry, new introductions can appear innocent for many years before ecological and economic damage becomes apparent, says the research organisation.

Evergreens, magnolia and holly make safer substitutes for Christmas decorations, says the USGS.

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