Tufted thallus with terete, narrow(1-3 mm) main branches which are often markedly shiny-blackened at the base and originate originating from a wide-spreading holdfast. The branches have conspicuous black pycnidal ostioles and button-like apothecia. On wind-exposed, siliceous, coastal rocks, often mixed with Ramalina siliquosa

References: 
Smith, C.W. et al. editors (2009) The Lichens of Great Britain and Irelandd
Dobson, F.S. (2018) Lichens: an Illustrated Guide to the British and Irish Species