''Cirsium hydrophilum'' is a species of
thistle which is
endemic to
California, where it is found only in the
San Francisco Bay Area and the
Sacramento-San Joaquin River Delta. This native thistle grows in wet
bog
A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...
gy habitats.
[
]
Description
''Cirsium hydrophilum'' may reach in height with a branching, cobwebby stem. The leaves are longest near the base of the plant, approaching in length. They are cut into toothed lobes and covered in spines, particularly along the petiole.[Flora of North America, ''Cirsium hydrophilum'' (Greene) Jepson, Fl. W. Calif. 507. 1901. ]
/ref>
The inflorescence bears one or more flower heads
A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...
, each up to long. The head is lined with sticky, twisted, spiny phyllaries and contains pink to purple flowers. The fruit is an achene
An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...
a long topped with a pappus of about centimeters.[
]
Varieties
There are two very localized varieties:
*The rare ''Cirsium hydrophilum'' var. ''hydrophilum'', the Suisun thistle, is known from two occurrences in the Suisun Marsh, in the salt marsh habitat of the Delta in Solano County. It is treated as a federally listed endangered species
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...
.
*The very rare ''Cirsium hydrophilum'' var. ''vaseyi'', Mt. Tamalpais thistle or Vasey's thistle, is known from about twenty occurrences on Mount Tamalpais in Marin County
Marin County is a county located in the northwestern part of the San Francisco Bay Area of the U.S. state of California. As of the 2020 census, the population was 262,231. Its county seat and largest city is San Rafael. Marin County is acros ...
, in Vacaville, California in Solano County, and inside the Presidio in the City of San Francisco
San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17th ...
. It is currently not a listed federal or state endangered species.Calflora taxon report, University of California, ''Cirsium hydrophilum'' (E. Greene) Jepson var. ''vaseyi'' (A. Gray) J. Howell, Mt. Tamalpais thistle, Vasey's thistle
/ref>
References
External links
Jepson Manual Treatment - ''Cirsium hydrophilum''The Nature Conservancy-NatureServe: ''Cirsium hydrophilum''
hydrophilum
Endemic flora of California
Natural history of the California chaparral and woodlands
Natural history of the Central Valley (California)
Natural history of Marin County, California
Taxa named by Willis Linn Jepson
Critically endangered flora of California
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