Didymodon nicholsonii Nicholson's Beard-moss

A dark brown-green or olive-green, acrocarpus moss which form tufts or large patches with boat-shaped leaves. It occurs naturally on stones and tree roots in the flood zone of rivers and streams, but it is much more common in Britain as a member of the tarmac bryophyte assemblage, where it has become common and is expanding its range. It is a lowland, Suboceanic species and is most common in the south of Britain, particularly in the west. It is widespread in West Glamorgan and appears to be common on tarmac in Swansea, but less common in the uplands of Neath Port Talbot. However, it may be under recorded. All British populations seem to be female and sporophyte capsules have only been recorded once.