The fern Asplenium trichomanes (Maidenhair spleenwort) growing on a stone wall in Keswick, Cumbria UK. The picture shows plants in midsummer; those to the top and left of the frame are showing browning due to drought. A. trichomanes has a Northern and Western distribution in Britain. It is widespread globally, occurring in most of Europe, the Himalayas, the Americas and New Zealand. In the form of an infusion, the leaves have been listed as a herbal medicine. Their action seems rather non-specific (emetic, expectorant, laxative).