Aposematic (Warning) Coloration in Plants

Aposematic (warning) coloration is a common defense in plants, although it was largely ignored before 2001. The fact that many aposematic animals use both plant-based pigments and sequestered poisonous molecules to become aposematic emphasizes the absurdity of neglecting the aposematic nature of so many plants. Similar to the situation in animals, aposematic coloration in plants is commonly yellow, orange, red, brown, black, white, or combinations of these colors. Aposematic coloration is expressed by thorny, spiny, prickly and poisonous plants, and by plants that are unpalatable for various other reasons. Plants that mimic aposematic plants or aposematic animals are also known. Many types of aposematic coloration also serve other functions at the same time, such as physiological, communicative and even other defensive functions. It is therefore difficult in many cases to evaluate the relative functional share of visual aposematism in various color patterns of plants and the specific selective agents involved in their evolution. Aposematic coloration is part of a broader phenomenon of defensive coloration in plants; this topic has also received only limited attention, as is evident from the lack of a regular and systematic description of these color patterns in published floras.