''Geothallus'' is a

monotypic genus In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

liverwort The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ...

in the family

Sphaerocarpaceae Sphaerocarpaceae is a family of liverworts known as bottle liverworts. Approximately ten species are included in this family, most of them in the genus '' Sphaerocarpos'', but one additional species in the genus ''Geothallus''. Distribution ...

family. It includes only the single species ''Geothallus tuberosus''. Its common name is Campbell's liverwort. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...

, where it is known only from

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...

and Riverside Counties.''Geothallus tuberosus''.
CNPS, Rare Plant Program. 2015. Inventory of Rare and Endangered Plants (online edition, v8-02). California Native Plant Society. Accessed 31 August 2015. This liverwort grows in moist coastal scrub habitat and

vernal pool Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the safe ...

s. At least one population occurs on the grounds of

Marine Corps Base Camp Pendleton Marine Corps Base Camp Pendleton is the major West Coast base of the United States Marine Corps and is one of the largest Marine Corps bases in the United States. It is on the Southern California coast in San Diego County and is bordered by Oc ...

, and it has also been noted on the Santa Rosa Plateau.

References

Sphaerocarpales Liverwort genera Endemic flora of California Bryophyta of North America Natural history of the California chaparral and woodlands Natural history of Riverside County, California Natural history of San Diego County, California Natural history of the Peninsular Ranges Monotypic bryophyte genera Critically endangered flora of California Taxonomy articles created by Polbot {{Bryophyte-stub