Hornworts are our least common bryophytes, as well as the least species-rich, with 200-300 species worldwide, 8 species in California, and 5 (possibly more) species in Santa Barbara County. With their rather amorphous form, consisting of a relatively thin, gelatinous thallus, and a seemingly simple, horn-like sporophyte, one might assume they are the most evolutionarily basal of the bryophytes, but in fact genetic studies reveal them to be the most closely related to the vascular plants. Here in southern California, individuals are few and far between, and somewhat challenging to study, as plants are fairly delicate, and many of the species-defining characters lie in the mature spores, which may not be available until the thallus has begun to dry and shrivel, along with its own defining characters.

Click on a thumbnail to navigate to a species page with detailed descriptions and many photos of key characters.