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Plant Profile

Surf Thistle (Cirsium rhothophilum)

Photo Credit: Cal. Native Plant Society

Global Rank: G1 - Critically Imperiled
Legal Status: N/A
Family: Asteraceae
State: CA
Nature Serve ID: 149012
Lifeform: Forb/herb
Date Inducted in National Collection:

Description:

Cirsium rhothophilum is a rare North American species of thistle known by the common name surf thistle. Cirsium rhothophilum grows up to 1 m tall with fleshy, woolly herbage usually forming a mound. The thick leaves are wavy and covered in felt-like hairs. They may have smooth, lobed, or toothed edges and small spines. The largest leaves at the base of the plant may reach 25 cm in length. The inflorescence bears several clustered flower heads which bloom from April through June, each head up to 4 centimeters long and 6 cm wide. The heads are lined with woolly phyllaries and filled with off-white to pale yellowish disc florets but no ray florets. The fruit is an achene a few millimeters long with a pappus up to 2 centimeters in length. [Calscape]

Where is Surf Thistle (Cirsium rhothophilum) located in the wild?

Habitat:

Cirsium rhothophilum grows in sand dunes and coastal scrub near the beach.

Distribution:

Cirsium rhothophilum is native to California, where approximately 20 plants exist on the coastlines of San Luis Obispo and Santa Barbara Counties.[CNPS]

States & Provinces:

Surf Thistle can be found in California

Which CPC Partners conserve Surf Thistle (Cirsium rhothophilum)?

Santa Barbara Botanic Garden

Not Sponsored

Conservation Actions

Assigned 06/13/17

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

09/01/2020

Based on an September 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden holds 1 accessions of Cirsium rhothophilum in orthodox seed collection. There are as many as 30 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

08/05/2020

Based on an August 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden has collected 1 seed accessions of Cirsium rhothophilum from 1 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 8 maternal plants