Dilated Scalewort - Frullania dilatata
Many thanks to Kay Newbury at Reading University for the identification only of this Liverwort species - Frullania dilatata.
A common liverwort on a variety of trees and shrubs, especially Ash (Fraxinus excelsior), Willow (Salix ssp.), Poplar (Populus ssp.), etc., can also occur on rock and in turf. Distinctive green or brown sub-pinnately branched leafy liverwort, leaves to 1mm (0.04in) wide and 1.2mm (0.05in) long, with rounded lobes. Dioecious, male shoots look relatively narrow, and female shoots have warty perianths.