With those scarlet berries and emerald leaves, Christmasberry cuttings might seem perfectly festive. But looks can be deceiving: decking the halls with this plant could very well bring more harm than holiday cheer. "Christmasberry (Schinus terebinthifolius) is in the same plant family (Anacardiaceae) as poison ivy and poison oak," says William Gregg of the U.S. Geological Survey (USGS). "It produces chemicals in its leaves, flowers and fruit that irritate skin and respiratory passages of susceptible, often unsuspecting people." Even outdoors, Christmasberry (right), also known as Brazilian peppertree, has been causing trouble. In the century that has passed since this vinelike tree was first brought to Florida from Brazil, it has invaded about 700,000 acres of land in the southern part of the state. There, as well as in Arizona, California and Hawaii, dense thickets of Christmasberry have displaced native plants and animals. Indeed, by the 1980s Christmasberry had earned the dubious distinction of being the Florida Everglades' most serious alien plant threat. Efforts to control this foreign species continue. In the meantime, the U.S.G.S. recommends not introducing it into your home.