About Anthoceros agrestis Paton
Anthoceros agrestis grows as a thin, dark green, rosette-shaped thallus that can reach up to 1.5 cm (0.6 in) in diameter. It superficially looks like a leafless liverwort. Its surface is dotted with hollows that hold the species' male organs. The spore-producing structures of this plant do not have a stalk or capsule, but instead grow erect, cylindrical formations that turn black when they reach maturity. These mature structures then split open to expose the spore-bearing central spindle and release the black spores. This hornwort has a circum-boreal distribution across temperate Europe and North America. It is a lowland species that grows in moist soil in arable fields and ditches. It is classified as vulnerable in the Irish Red Data Book, since it has been recorded from fewer than five locations across Ireland. It is found at only one location in Northern Ireland, in County Down, and due to its rarity there, it is designated a Northern Ireland Priority Species.