Phaeoceros spp.


 Species of Phaeoceros are typically found in mild climates of subcosmopolitan areas.


Overall Structure:

The thallus is flattened, with a rossette of thalloid branches.


The branches resemble radiating, overlapping, and dichotomously lobed leaves.  There is no midrib on the thallus.  The upper cells of the thallus contain an abundance of chloroplasts, while the lower cells do not contain chloroplasts.  The chloroplasts are spindle- or lens-shaped and contain a pyrenoid surrounded by starch.

Shoots of Phaeoceros spp. typically form a symbiotic relationship with algal colonies of Nostoc. The hornwort recieves Nitrogen, while the alga receives moisture and protection.

The majority of Phaeoceros spp. are bisexual.  The sexual reproductive structures are embedded within the dorsal surface of the thallus.


As with other hornwort species, the rhizoids are unicellular, thin-walled, and smooth.


The sporophytic generation has one or two vertical lines of dehiscence.  The epidermis of the sporophyte is stomate, with the guard cells of the stomata containing starch-filled plastids.