A raw afternoon; frost gripping the blackthorn. All along the hedgerow, the spiny barbs glinted with ice – a glacial white casing the black. Although day was already fading, something made me stop for a closer look. Deep within the swirl of thorns, the blackthorn twigs were touched with gold, as though somehow the rays of the summer sun were caught in the wintry thorn hedge. It was Xanthoria parietina, also known as common orange lichen, or sunburst.