Dangerous Plants and Weeds You Should Never Touch
Eww! 10 Smelly Plants That Are Making Your Garden Stink
(Heracleum mantegazzianum and H. sphondylium)
Hogweed is an invasive plant that grows throughout North America, but it is a particular nuisance along the Atlantic coast. The pain of hogweed, both giant (Heracleum mantegazzianum) and common (H.sphondylium), comes from the sap of the leaves, which can cause phytophotodermatitis, a chemical reaction that occurs when the sap touches the skin and is then exposed to sunlight. The result is painful, severe blisters on the surface of the skin. If it comes into contact with eyes, it can also cause blindness.
This flowering tree (also known as the “beach apple”) is native to the tropical climes of South America and southern North America (i.e. Florida). It has the reputation of being the world’s most dangerous tree, and for good reason. Every part of the tree is poisonous, including the small round fruits of the manchineel, which have been known to be fatal if ingested. The sap contains irritants that create a blistering reaction upon contact with skin.
If you’ve spent much time outdoors in the South, you’ve probably happened upon some poison ivy. You’ve probably also become familiar with the old saying “leaves of three, let it be!” It’s a reminder to stay away from this painful and skin-irritating three-leaved vine. That property is thanks to "urushiol,” an oil in the ivy leaves that irritates when it comes into contact with skin. Learn more.
This woody vine is in the sumac family and packs a painful punch. Its sap also contains the irritant urushiol, which prompts a reaction when it touches and is absorbed into the skin. Poison oak is sometimes mistaken for poison ivy, though it can be distinguished by its shrub form and its leaves, which look much like the leaves of an oak tree.
Poison sumac is a woody shrub that can be found in wetland areas. Touching it is also a direct route to a painful rash. In the South, it’s also commonly known as thunderwood. Not all sumac shrubs are dangerous, but poison sumac definitely is. It appears as a shrub, with stems filled with pinnately compound leaves (i.e. leaves growing in pairs). It also has clusters of green berries. Harmless sumac, on the other hand, has red berries.
Pain and itching follow a brush with a stinging nettle. Its leaves and stems are covered in tiny stinging hairs, which release irritants when they come into contact with skin. Touching these needle-like spines will make skin sting (hence the name), and sometimes break out in inflammation.