Orange Rock Hair

''Trentepohlia aurea'' is a species of filamentous terrestrial green alga with a worldwide distribution. It grows on rocks, old walls and the trunks and branches of trees such as oaks and the Monterey cypress where the tree occurs in coastal central California. The orange coloration results from carotenoid pigments in the algal cells. It is probably the most widespread and abundant species of ''Trentepohlia'' in the Britain and Ireland.