Anthoceros punctatus

HomeLearningSpecies FinderAnthoceros punctatus

Identification notes

When A. punctatus has ‘horns’ (slender bivalved sporophytes) it is immediately identifiable as one of our four species of hornworts. Without them, it can look like a number of thallose liverworts (especially Blasia pusilla). Its identity can be pinpointed by a hand-lens search for the small scattered opaque dots in the thallus that are colonies of Nostoc, a cyanobacterium. All of our hornworts have these, as does Blasia pusilla, although the colonies in that species are restricted to a single line on each side of the thallus rather than being scattered about. Hornworts also lack oil-bodies and are differentiated from all liverworts by large solitary plate-like chloroplasts in gametophyte cells.

All but one (Phaeoceros laevis) of our hornworts are monoicous and even if horns are lacking or immature, antheridial cavities can usually be found – these look like small warts or pits scattered on the upper thallus surface. Each contains a number of small orange stalked antheridia which can be forced out by applying gentle pressure to the mouth of the cavity with a pair of forceps. Measuring their width under a high power microscope is important in determining the species, and even the genus – the antheridia of Anthoceros being much smaller than Phaeoceros. Well-grown A. punctatus is also usually obviously frilly-looking and slightly transparent, whereas Phaeoceros species have opaque, leathery-looking thalli that are not deeply incised.

Read the Field Guide account

Distribution in Great Britain and Ireland

View distribution from the BBS Atlas 2014

Similar Species