club pincushion moss

Ulota coarctata, the club pincushion moss, is an epiphytic moss in the family Orthotrichaceae, growing on the bark of deciduous and occasionally coniferous trees in Europe and North America. The genus Ulota is characterized by strongly crisped and contorted leaves when dry that straighten upon wetting, a hygroscopic response that aids in identifying these mosses in the field. U. coarctata forms small, compact, cushion-like tufts on branches and trunk surfaces, typically on trees with nutrient-rich, rough-barked species such as elder, hazel, and ash. It is listed as Vulnerable by the IUCN, reflecting declines associated with atmospheric pollution, particularly sulfur dioxide emissions that historically acidified bark surfaces and eliminated sensitive epiphytic bryophyte and lichen communities across much of western Europe. Since reductions in air pollution since the 1970s, some orthotrichaceous mosses have begun recovering in previously polluted regions. U. coarctata requires relatively clean air conditions and adequate atmospheric moisture, making it a useful bioindicator of air quality. Conservation depends on continued air quality improvement and retention of mature deciduous trees.