Boulder fields and screes are important for the chasmophytic flora present, which in Wales usually refers to the pteridophyte flora, e.g. species such as brittle bladder-fern (Cystopteris fragilis), green spleenwort (Asplenium viride) and parsley fern (Cryptogramma crispa). These habitats are difficult to survey or monitor on the ground but are ideally suited to drone survey.