Cirsium hydrophilum

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Cirsium hydrophilum
Cirsium hydrophilum hydrophilum.jpg
Suisun thistle

Critically Imperiled (NatureServe)
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Asteraceae
Tribe: Cynareae
Genus: Cirsium
Species: C. hydrophilum
Binomial name
Cirsium hydrophilum
(Greene) Jeps.
  • Carduus hydrophilus Greene
  • Cirsium vaseyi var. hydrophilum (Greene) Petr.
  • Cirsium montigenum Petr.
  • Cirsium vaseyi (A.Gray) Jeps.
  • Cnicus breweri var. vaseyi A.Gray

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 boggy habitats.[2]


Cirsium hydrophilum may reach 2 metres (6.6 ft) in height with a branching, cobwebby stem. The leaves are longest near the base of the plant, approaching 90 centimetres (35 in) in length. They are cut into toothed lobes and covered in spines, particularly along the petiole.[2]

The inflorescence bears one or more flower heads, each up to 3 centimetres (1.2 in) long. The head is lined with sticky, twisted, spiny phyllaries and contains pink to purple flowers. The fruit is an achene a 2–4 millimetres (0.079–0.157 in) long topped with a pappus of about 1.5 centimetres (0.59 in) centimeters.[2]


There are two very localized varieties:


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