More than 150 native plants call the Florida Keys their home and a few people can identify all of them. However, the poisonwood tree is one plant that everyone, both residents and visitors, should learn to identify. “Why?” you ask.
Poisonwood – the Good:
Although poisonwood may not be considered man’s best friend, it provides food for numerous migratory and local birds. The poisonwood has male and female flowers on separate trees. The female poisonwood has loose clusters of small green and yellow flowers that appear from late winter through late summer, and produce an abundance of small, orange, oblong fruits. This fruit is a major food source for many birds, including the endangered white-crowned pigeon, which consumes it in large quantities during nesting season.
Poisonwood – the Bad:
The poisonwood is a member of the cashew family, which also includes poison ivy, poison sumac, poison oak and, perhaps surprisingly, mango. All parts of the tree contain a resin called urushiol, which can cause rashes and mucous membrane irritation in humans. It is so potent that people have even been affected by water dripping off poisonwood leaves, and by inhaling smoke from burning parts of the poisonwood.
Areas with only a few poisonwood may have signs posted, but this is not practical for native areas. Everyone entering native areas where poisonwood is known to grow should learn how to identify it prior to their hike. Unlike its relatives, poison ivy and poison oak, the leaf of poisonwood only occasionally has three leaflets; the norm is five and often there are seven. The leaflets are glossy dark green above and lighter below, and may have black blotches on them. The outer edge of the oval shaped leaflet is outlined in pale yellow and appears to be smooth. It has a distinctive yellow vein in the center. The poisonwood is semi-deciduous and tends to shed some of its leaves in the late fall or early winter.
“What if the leaves are not visible?” If you look at the trunk of the tree, young trees usually have gray bark while mature trees have red-tinted brown bark that flakes off in patches. Underneath the top layer of bark is an orange underbark, which may be covered in black patches. These black patches are the clear sap, which turns black when exposed to air.
Poisonwood the Ugly:
“What do I do if exposed to poisonwood?” As soon as possible, apply Tecnu Original Poison Oak & Ivy Outdoor Skin Cleanser according to directions. Also, launder all clothing and clean pets and tools with Tecnu. If you develop a minor rash, home treatment usually works; however, for a severe reaction you should seek medical attention. On your next walk be aware of your surroundings and beware of the poisonwood. They are only one of over a hundred native plants in the Florida Keys’ state parks.
Plan a visit at floridastateparks.org and experience “the Real Florida.” Susan Matthews is a volunteer at John Pennekamp Coral Reef State Park.