{{Short description|Monotypic genus of liverwort endemic to California}} {{Speciesbox | image = The structure and development of mosses and ferns (Archegoniatae) (1918) (14598320719).jpg | image_alt = | image_caption = | status = CR | status_system = IUCN3.1 | status_ref = <ref name=IUCN>{{cite iucn |last1=Doyle |first1=W.T. |year=2012 |title=''Geothallus tuberosus'' |volume=2012 |article-number=e.T39242A2895685 |doi=10.2305/IUCN.UK.2012-1.RLTS.T39242A2895685.en |access-date=14 November 2021}}</ref> | status2 = G1 | status2_system = TNC | status2_ref = <ref name=NS>{{cite NatureServe |id=2.126450 |title=''Geothallus tuberosus'' |access-date=28 November 2025}}</ref> | genus = Geothallus | parent_authority = Campb. | species = tuberosus | authority = Campb. | synonyms = {{Species list |Geocarpus tuberosus|(Campb.) K.I.Goebel |Sphaerocarpos tuberosus|(Campb.) R.M.Schust.}} | synonyms_ref = <ref name=WFO>{{cite WFO |id=0001196336 |title=''Geothallus tuberosus'' Campb. |access-date=28 November 2025}}</ref> }}
'''''Geothallus''''' is a monotypic genus of liverwort in the family Sphaerocarpaceae. Its sole species, '''''Geothallus tuberosus''''', is a critically endangered species endemic to California in the United States. Described in 1896 by American botanist Douglas Houghton Campbell, it is commonly known as '''Campbell's liverwort'''.
==Taxonomy and history== ''Geothallus tuberosus'' was described by American botanist Douglas Houghton Campbell in a 1896 article published in the ''Botanical Gazette''.<ref name=WFO/><ref>{{cite journal |last1=Stotler |first1=Raymond E. |last2=Crandall-Stotler |first2=Barbara |year=2017 |title=A Synopsis of the Liverwort Flora of North America North of Mexico |journal=Annals of the Missouri Botanical Garden |volume=102 |issue=4 |page=621 |doi=10.3417/2016027 |issn=00266493 |oclc=45446666}}</ref> Campbell first noticed the new species in March 1895, having found an unfamiliar plant growing in a clump of ''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, 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.<ref name="Campbell 1896">{{cite journal |last1=Campbell |first1=D.H. |author1-link=Douglas Houghton Campbell |year=1896 | title=A new Californian Liverwort |journal=Botanical Gazette |volume=21 |pages=9–13, pl. 2 |doi=10.1086/327288 |doi-access=free |issn=1940-1205 |oclc=45446737}}</ref> The generic epithet ''Geothallus'', meaning "earth thallus", refers to the way in which the plant grows affixed to the soil.<ref name=genera>{{cite book |last1=Schofield |first1=W.B. |year=2002 |title=Field Guide to Liverwort Genera of Pacific North America |publisher=Global Forest Society and University of Washington Press |location=San Francisco |pages=108–109 |isbn=0295981946}}</ref>
==Distribution and habitat== Endemic to California in the United States, ''Geothallus tuberosus'' is known only from San Diego County and Riverside County. It can be found in small, isolated populations on mesas, coastal hills, and the Peninsular Ranges, where it grows in sandy or gravelly soil, at the edges of vernal pools, and on flat and gently sloping areas in and near chaparral. It requires semi-shaded, moist conditions,<ref name=IUCN/><ref>{{cite journal |last1=Doyle |first1=William T. |last2=Stotler |first2=Raymond E. |year=2006 |title=Contributions toward a Bryoflora of California III. Keys and annotated species catalogue for liverworts and hornworts |journal=Madroño |volume=53 |issue=2 |pages=119–120 |doi=10.3120/0024-9637(2006)53[89:CTABOC]2.0.CO;2 |issn=0024-9637 |oclc=213802384}}</ref> and is considered very rare within its range.<ref name=genera/>
==References== {{Reflist}}
{{Taxonbar|from=Q13060343|from2=Q5471017}} {{Authority control}}
Category:Sphaerocarpales Category:Liverwort genera Category:Endemic flora of California Category:Natural history of the California chaparral and woodlands Category:Natural history of Riverside County, California Category:Natural history of San Diego County, California Category:Natural history of the Peninsular Ranges Category:Monotypic bryophyte genera Category:Critically endangered flora of California Category:Taxonomy articles created by Polbot
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