Orthotrichum diaphanum White-tipped Bristle-moss

An autoicous, acrocarpous moss which grows in tufts on nutrient-rich  bark, e.g. on Elder (Sambucus nigra) and also, quite commonly, on walls and other stone or rocky surfaces. The leaves have a conspicuous white tip which gives plants a hoary appearance and a superficial resemblance to a Schistidium species. The most likely source of confusion is Schistidium crassipilum, with which it might grow, but the overall growth forms and the capsules of the two species are different. The capsules of Orthotrichum diaphanum are pale brown and furrowed, especially when dry (see photo). It is quite tolerant of air pollution and it was one of the few mosses that was common on walls and masonary in the towns and cities of industrial areas in Britain when air quality was poor in the 20th Century. It is found throughout Britain except for the north of Scotland and it is largely an urban species of walls, stone or concrete structures in West Glamorgan and it appears to be less common as an epiphyte.