Cyanogenic polymorphism in bracken in relation to herbivore predation

Abstract

THE ecological success of bracken is partly a result of its extensive rhizome system, and because of its ability to synthesise various secondary compounds which deter predators and phytopathogens1-3. These compounds include the cyanogenic glycoside, prunasin4, toxic because onenzymatic hydrolysis HCN is released. Although present in only 5% of ferns5, cyanogenic glycosides are ecologically significant in other plant species; they deter both molluscs and voles from grazing on Lotus corniculatus6, and rabbits from eating Trifolium repens7. As in these two species, we have found that cyanogenesis is also polymorphic in bracken. © 1975 Nature Publishing Group.