Anthoceros

Species of Anthoceros are characterized by having a small to medium-sized, green thallus that is more or less lobed along the margins.[1] The spores are dark gray, dark brown or black, this is the easiest way to distinguish Anthoceros from the related genus Phaeoceros, which produces spores that are yellow.[1][2]

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.[3] The Nostoc colonies are present on the lower ventral surface and are visible as blue-green patches which open outwards by slime pores.

This hornwort grows in moist clay soils on hills, in ditches, and in damp hollows among rocks. The adult plant body is a gametophyte.

Species include:[4]

• Anthoceros agrestis
• Anthoceros himalayensis
• Anthoceros hispidus
• Anthoceros lamellatus
• Anthoceros neesii
• Anthoceros punctatus
• Anthoceros sambesianus
• Anthoceros scariosus
• Anthoceros tristanianus