This is a minute, immediately recognisable leafy liverwort that is unlikely to be found without careful searches of its preferred habitat. It especially likes humid, wooded ravines in the north and west where it can be found growing on well-decayed tree stumps and other dead wood, as well as on the rough bark of birch, oak and other living trees.
If you are in such a ravine, look for suitable living/deadwood habitat, ideally on the upper ravine banks in the vicinity of waterfalls or cascades. Then, scan the wood slowly for tiny, bright red dots raised above the surface. These are the gemmiferous shoots, which though minute, do catch the eye. A. hellerianum often grows in deep shade on the sides of decaying stumps and trees, and close-up searching of the lower parts will often reveal the gemmiferous shoots in profile. It grows in a community of other characteristic species, including Cephalozia curvifolia, Scapania umbrosa, Syzygiella autumnalis and Tritomaria exsectiformis although these species are all considerably larger.
Under the microscope, the angular, single-celled bright red gemmae are distinctive.Read the Field Guide account