Allelopathy 

Bracken is an allelopath - it produces chemicals that supress the germination of seeds. Wood Anemone, Bluebell, Foxgloves and Chickweed Wintergreen seem immune ti the suppression. Bracken is carcinogenic but is useful cover for Pearl Bordered Fritillaries. It is eaten by the caterpillars of the following moths - brown silver-line, small angle shades, orange swift, gold swift and map-winged swift moths.