This dubious honour must go to the manchineel tree Hippomane mancinella, found in brackish habitats in northern South America, the Caribbean and Florida.
It bears an apple-like fruit, which, along with its sap, contains an eye-poppingly strong poison that can cause severe blisters if it makes contact with human skin.
Such toxicity in its fruits means that the tree can’t rely on mammals’ digestive systems to disperse its seeds, depending instead on the tides and currents of its coastal home.
A warning sign on a manchineel tree. © Brett Charlton/Getty
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Main image: Machineel tree in the Galápagos Islands. © Getty