Species of Anthoceros are found growing exposed to sun and shade. Anthoceros spp. can be found on mineral soil, ditches, terraces, and irrigated sites.
Hornworts are not competitive and are usually alone or with very few other species growing in disturbed areas, thus they are considered pioneer species.
The thallus is irregularly shaped, not bilaterally symmetrical (as is common with hornworts), compressed, dark green, and has a smooth surface.
The thallus has overlapping flaps that are irregularly branched and is composed of mucilage chambers and parenchyma cells. Internal differentiation of the thallus is via the mucilage canals. Commonly, Nostoc colonies seek protection within the mucilage clefts.
Pores are located ventrally on the thallus. However, the air chambers are not true air chambers.
There is a single plastid per cell, pyrenoids are in the middle of the chloroplasts. Oil bodies are simple.
Rhizoids are smooth and unicellular.
Gametangia (male and female) develop along the dorsal midline of the thallus. There is one antheridium per chamber and are embedded within the thallus. There are no paraphyses.
Archegonia are embedded in the thallus. There are no paraphyses.
Sporophytes are brownish in color and emerge from sleeves of thalloid tissue. The thallus- calyptra is left at the base of the mature sporophyte.
The sporophyte has a foot, columella, spore layer, multicellular jacket (with no band thickenings) and elators. The small foot is surrounded by a layer of epidermal cells. The sporangium has a surrounding cuticle. There is no seta.
The sporangial jacket has 2-3 indentations where the lines of dehiscence will be located. Thus, there are 2-3 lines of dehiscence. The sporangial jacket contains stomata with guard cells, primarily functioning in gas exchange.
The growth of the sporangium is indeterminate. Spores are dispersed via a “tier/conveyer belt” dispersal method, referring to the differing ages of spores in the sporangium. Spores adhere in tetrads until they are shed. Pseudo-elators are present and help to disperse and nourish spores. The pseudo-elaters are multicellular.
Historically, spore ornamentation of Anthoceros spp. were compared to Streelispora spp. and Aneurospora spp. (ancient organisms). This comparison provided weak evidence to support the presence of bryophytes in the Siluran period.
Asexual reproduction is via fragmentation. There is essentially no protonema for hornworts.