This tall, handsome tree grows in sandy soils along the coastlines of the Caribbean and South America, but it literally oozes toxic chemicals from all of its parts.
And I do mean all: it’s fruit, "manzanillas de la muerte" or "little apples of death," have a deceptively sweet flavor. But after one bite, you'll notice a weird peppery taste, which then turns into a burning, painful tightness in your throat. Contact with the sap can cause your skin to blister. And smoke from burning manchineel wood can cause temporary blindness.
The poisonous nature of this tree seems counter to the principles of evolution. Most trees have evolved fruits to attract animals to spread their seeds to places that are safe for germination. But this tree’s toxicity means that typical dispersers — birds and mammals —completely avoid them. Instead, these seashore-dwelling trees drop their fruits into the water, and the tides and currents of the ocean disperse the seeds to successfully colonize new places.
What about trees that are toxic to other plants? Some trees, like black walnuts, exhibit allelopathy, a sort of chemical warfare among plants when one plant releases chemicals that suppress the germination or growth of other plants. These compounds move into the soil from decomposing leaves or roots, which stunts or kills the neighboring plants, leaving more nutrients, water and sunlight available for the plant aggressor.
But some poisonous trees have positive properties. People use the wood of the machineel tree to make furniture, felling the trees by burning instead of using axes. And these trees act as natural windbreaks countering the forces of beach erosion, which is critical in the face of rising sea levels. Indigenous groups have also used manchineel as medicine, using its fruits as a diuretic.
So, although there are a few trees that cause harm, even the most toxic of them have uses that redeem them.
