Identification notes

Even if you don’t recognise this remarkable-looking rare thallose liverwort, its opaque thallus with numerous surface pores and somewhat indistinct areolae will probably bring to mind some of its common relatives in the Marchantiales…Marchantia polymorpha, Conocephalum conicum and Lunularia cruciata for example.

Fortunately, it’s almost invariably found fertile and the female involucres (the specialised flaps which surround and protect the receptacles at the end of the thallus) are bivalved and glossy black, and resemble a strange clam. As plants dry, these arch upwards and become even more conspicuous. There’s really nothing else like it in our liverwort flora.

Distribution in Great Britain and Ireland

Don’t be surprised if you come across Targionia in a place that looks highly unsuitable for such a rare species – it has a penchant for scruffy places such as road banks and railway cuttings, as well as more natural habitat such as rock exposures.