# Geothallus

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***Geothallus*** is a [monotypic genus](/source/Monotypic_genus) of [liverwort](/source/Marchantiophyta) in the family [Sphaerocarpaceae](/source/Sphaerocarpaceae). Its sole species, ***Geothallus tuberosus***, is a [critically endangered](/source/Critically_endangered) species [endemic](/source/Endemic) to [California](/source/California) in the United States. [Described](/source/Species_description) in 1896 by American [botanist](/source/Botanist) [Douglas Houghton Campbell](/source/Douglas_Houghton_Campbell), it is commonly known as **Campbell's liverwort**.

## Taxonomy and history

*Geothallus tuberosus* was [described](/source/Species_description) by American [botanist](/source/Botanist) [Douglas Houghton Campbell](/source/Douglas_Houghton_Campbell) in a 1896 article published in the *[Botanical Gazette](/source/Botanical_Gazette)*.[1][2] Campbell first noticed the new species in March 1895, having found an unfamiliar plant growing in a clump of *[Ophioglossum nudicaule](/source/Ophioglossum_nudicaule)* he was cultivating. The *O. nudicaule* had been sent to him by a Katherine Brandegee, who collected them from sandy soil near [San Diego](/source/San_Diego), California. Mixed in with the *O. nudicaule*, the specimens were partially buried in the dirt and had lost much of their green colour due to desiccation. Campbell would only notice their uniqueness after rehydrating the clump of plants under a [bell jar](/source/Bell_jar).[3] The [generic epithet](/source/Generic_epithet) *Geothallus*, meaning "earth [thallus](/source/Thallus)", refers to the way in which the plant grows affixed to the soil.[4]

## Distribution and habitat

[Endemic](/source/Endemic) to [California](/source/California) in the United States, *Geothallus tuberosus* is known only from [San Diego County](/source/San_Diego_County) and [Riverside County](/source/Riverside_County). It can be found in small, isolated populations on [mesas](/source/Mesa), coastal hills, and the [Peninsular Ranges](/source/Peninsular_Ranges), where it grows in sandy or [gravelly](/source/Gravel) soil, at the edges of [vernal pools](/source/Vernal_pool), and on flat and gently sloping areas in and near [chaparral](/source/Chaparral). It requires semi-shaded, moist conditions,[5][6] and is considered very rare within its range.[4]

## References

1. "*Geothallus tuberosus* Campb.". 0001196336. Retrieved 28 November 2025.

1. Stotler, Raymond E. & Crandall-Stotler, Barbara (2017). "A Synopsis of the Liverwort Flora of North America North of Mexico". *[Annals of the Missouri Botanical Garden](/source/Annals_of_the_Missouri_Botanical_Garden)*. **102** (4): 621. [doi:10.3417/2016027](https://doi.org/10.3417/2016027). [ISSN 00266493](https://www.worldcat.org/issn/00266493). [OCLC 45446666](https://www.worldcat.org/oclc/45446666)

1. Campbell, D.H. (1896). "A new Californian Liverwort". *[Botanical Gazette](/source/Botanical_Gazette)*. **21**: 9–13, pl. 2. [doi:10.1086/327288](https://doi.org/10.1086/327288). [ISSN 1940-1205](https://www.worldcat.org/issn/1940-1205). [OCLC 45446737](https://www.worldcat.org/oclc/45446737)

1. Schofield, W.B. (2002). *Field Guide to Liverwort Genera of Pacific North America*. San Francisco: [Global Forest Society](/source/Global_Forest_Society) and [University of Washington Press](/source/University_of_Washington_Press). pp. 108–109. ISBN 0295981946.

1. Doyle, W.T. (2012). "*Geothallus tuberosus*". Vol. 2012. [doi:10.2305/IUCN.UK.2012-1.RLTS.T39242A2895685.en](https://doi.org/10.2305/IUCN.UK.2012-1.RLTS.T39242A2895685.en). Retrieved 14 November 2021.

1. Doyle, William T. & Stotler, Raymond E. (2006). "Contributions toward a Bryoflora of California III. Keys and annotated species catalogue for liverworts and hornworts". *[Madroño](/source/Madro%C3%B1o_(journal))*. **53** (2): 119–120. [doi:10.3120/0024-9637(2006)53\[89:CTABOC](https://doi.org/10.3120/0024-9637(2006)53%5B89:CTABOC%5D2.0.CO;2)2.0.CO;2]. [ISSN 0024-9637](https://www.worldcat.org/issn/0024-9637). [OCLC 213802384](https://www.worldcat.org/oclc/213802384)

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Adapted from the Wikipedia article [Geothallus](https://en.wikipedia.org/wiki/Geothallus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Geothallus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.