Harsh environments provide important insights into ecology and evolution, and serpentine soils are a classic example of a harsh habitat. Serpentine soils are generally deficient in plant essential nutrients such as nitrogen, phosphorus, potassium, sulphur; have a calcium to magnesium (Ca:Mg) molar ratio of less than 1; and have elevated levels of heavy metals such as nickel, cobalt, and chromium. Due to the high degree of abiotic stress and insular nature of serpentine outcrops, serpentine-associated organisms are model organisms for the study of adaptation, ecotypic differentiation, and speciation. Recent research has developed plants growing on these soils into a model system for exploring plant adaptation and evolutionary innovation. One such innovation is nickel hyperaccumulation. The term “hyperaccumulator” denotes plants that take up and sequester relatively large amounts of metals in their aboveground tissues. Five hypotheses have been suggested to explain the evolution of metal hyperaccumulation by plants, including that of defense against herbivores and pathogens. Other ecological consequences of nickel hyperaccumulation besides defense, including the mobilization of nickel in serpentine ecosystems, are now being investigated. In this symposium, we bring together international researchers to explore major topics in plant ecology and evolution in these environments.