Anthoceros is a genus of hornworts in the family Anthocerotaceae. The genus is global in its distribution.
Its name means 'flower horn', and refers to the characteristic horn-shaped sporophytes that all hornworts produce.
The dark color of the spores is the easiest way to distinguish Anthoceros from the related genus Phaeoceros, which produces spores that are yellow as noted by Campbell (1939).
The genus is distinguished by having spores that are dark brown to black, a relatively frilly thallus when compared to Phaeoceros, and larger and more internal cavities than Phaeoceros.
The sporophytes of Anthoceros are larger and much more complex than those of Riccia, Marchantia, and Pellia.
It is differentiated into a foot, a constriction like intermediate zone and a capsule.
There is no seta.
It arises in clusters from the dorsal surface of the thallus each surrounded at the base a tubular involucre.
Anthoceros species are host to species of Nostoc, a symbiotic relationship in which Nostoc provides nitrogen to its host through cells known as heterocysts, and which are able to carry out photosynthesis.
This hornwort grows in moist clay soils on hills, in ditches, and in damp hollows among rocks.
The adult plant body is a gametophyte.
The Nostoc colonies are present on the lower ventral surface and are visible as blue-green patches which open outwards by slime pores.
The thallus is translucent and sub-orbicular in outline.
