Florida Un-Friendly Plants

October is here, and horrors lurk everywhere you look... zombies, vampires, werewolves, and millions of tiny Elsas from Frozen knocking at your door and demanding candy. Our gardens can be full of horrors too, with fire ants and yellow jackets and paper wasps (oh my!), and dangers can lurk even among our plants. Here's a look at some of the unfriendly plants that haunt Central Florida yards and gardens. (Click the links for more info and photos for each plant.)

Sandspur (Cenchrus sp.) 

The Thorny Bunch

Sandspur (Cenchrus spinifex and C. echinatus): Sandspur makes itself known starting in late summer, when the spiky seed heads covered in spiny burs mature. Evolved to stick to the fur of passing animals for widespread distribution, these burs will also attach themselves to human skin. That can be fairly painful, especially since our first instinct is to grab the bur with our fingers to remove it - thereby poking ourselves in the hands too. Fortunately, once removed, sandspurs don't seem to cause any type of rash or reaction.

Coralbean (Erythrina herbacea): The tubular red flowers of this native shrub attract butterflies and other pollinators, making it a great addition to a Florida Friendly yard. Take caution, though - this shrub also has nasty thorns on its branches that make it unpleasant to prune. This shrub is best added to areas where it can grow freely without needing much attention from humans.

Saw Palmetto (Serenoa repens): The attractive fan-shaped foliage of saw palmetto makes it a favorite in many landscape designs. However, the name betrays the downfall of this plant - its thick stems are lined with sharp thorns that can inflict nasty damage to the unwary. Be cautious when pruning saw palmetto to avoid injury, or plant it in a location where little maintenance is required.

Wild Lime (Zanthoxylum fagara) and Hercules Club (Zanthoxylum clava-herculis): These two members of the citrus family are native to Florida and serve as host plants for the Giant Swallowtail. Both are armed with sharp thorns of varying size, depending on the age of the growth on which the spines appear. These hooked thorns often embed themselves in skin and break off, where they can easily become infected.

Wild Lime (Zanthoxylum fagara)

The Toxic

Castor Bean (Ricinus communis): Popularly grown as an ornamental worldwide, the Castor Bean plant is used to make castor oil, which has long had medicinal applications. However, the raw bean also contains ricin, with four beans being enough to kill a human (in a very miserable fashion), which gives this plant the title of the most poisonous in the world. Castor Bean can also cause a strong allergic reaction with its pollen, and the foliage can cause rashes in those with sensitivity.

American Nightshade (Solanum americanum): This native wildflower can be particularly dangerous because it grows berries which may tempt children. Unripe berries are particularly toxic (thanks to the glycoalkaloids solanine and solamargine), with just a handful being enough to kill a small child, but ripe berries and foliage are dangerous too.

Oleander (Nerium oleander): The beautiful flowering shrub is used frequently in landscapes in Florida, but it happens to be pretty toxic if ingested in large amounts due to the compound oleandrin. There have been few human deaths reported in the U.S. due to oleander, but care should be taken to keep children and dogs away from this plant.

Oleander (Nerium oleander)

The Attackers

Tread Softly (Cnidoscolus stimulosus): This well-named wildflower, also called Spurge Nettle, has a pretty white flower in spring that invites you to come closer, and urticating hairs that punish you when you do. Tiny hairs on the leaves cause a stinging sensation that persists for up to an hour, followed by a red rash. This low-growing plant is often mixed in with other spring growth, making it hard to see until you accidentally brush against it and pay the price.

Poison Ivy (Toxicodendron radicans): Most people are familiar with this nasty vine and the old adage, "Leaves of three, let it be." All parts of the poison ivy plant contain an irritating oil called urushiol. Contact with this oil may cause dermatitis (sometimes extreme) in some people. Poison ivy does have its benefits; many songbirds seek out and enjoy the berries it produces.

Common Rue (Ruta graevolens): This herb is useful for butterfly gardeners, as it serves as a host plant for both Giant Swallowtails and Black Swallowtails. However, the oils produced by the plant are phytophototoxins. When someone with a rue sensitivity gets the oils on their skin, and then exposes their skin to UV rays from sunlight, they may develop blisters which, while not particularly painful, persist for quite some time.

Common Rue (Ruta graevolens) with Black Swallowtail caterpillars