Colura calyptrifolia Fingered Cowlwort

Colura calyptrifolia is a tiny, epiphytic, hyper-oceanic liverwort that has undergone a spectacular range expansion in recent decades. For most of the last millenium it was known only from sheltered ravines, wooded streamsides, lakesides, rocky coasts and damp montane cliffs, mostly in western Scotland, Ireland and north Wales, growing on rock and also as an epiphyte. Since then it has rapidly colonised humid conifer plantations in south Wales where it is found almost exclusively as an epiphyte growing on conifers, hardwood trees and shrubs (including Buddleja davidii) as well as Heather (Calluna vulgaris) and Gorse. It was first recorded in Glamorgan on a Willow in Hensol Forest by Tom BlockeelI in 1985 and at that time was regarded as a very rare species in the county flora. It is now an ubiquitous component of the epiphytic floa of willows in Sitka Spruce plantations in West Glamorgan, particularly in the Neath and Afan Valleys where it was completely unknown 30 years ago. It is commonly associated with Metzgeria species, Ulota species, Orthotrichum species, Cryphaea heteromalla and Zygodon conoideus var. conoideus. However, there are few records of it from Gower. It will grow on lots of hardwood trees as well as Buddleja davidii, Vaccinium myrtillus, Calluna vulgaris and arteficial substrates such as discarded bottles and other household items. A comparison of its distribution in West Glamorgan with that of Sitka Spruce (Picea sitchensis) shows a significant correspondence. Sam Bosanquet has suggested that the range expansion of Colura calyptrifolia  in Wales has been expediated in areas where dense forests of conifers have helped to create a suitable hyperoceanic mesoclimate conducive to rapid growth and spore production. It is autoicous and perianths are common.