CPC Plant Profile: California Jewelflower
Search / Plant Profile / Caulanthus californicus
Plant Profile

California Jewelflower (Caulanthus californicus)

Flowers of Caulanthus californicus Photo Credit: Aaron Schusteff
Description
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: Federally Endangered
  • Family: Brassicaceae
  • State: CA
  • Nature Serve ID: 153225
  • Date Inducted in National Collection: 09/18/2021

California jewel flower, an annual in the mustard family, germinates after winter rains and flowers from February through May. Plants are typically branched, with clasping leaves. The striking inflorescences appear to have flowers that appear purple or white, sometimes green- to purple-tinged near the sepal tips of upper flowers. Open flowers bear white to greenish sepals, and narrow, crinkly, white petals (Rollins 1993). However, the dark purple terminal flower buds remain closed, and may provide a striking contrast to reproductive flowers for the purpose of attracting insects. Once widespread in the southern San Joaquin Valley and adjacent foothills, it is now restricted to three general areas of Fresno, San Luis Obispo, and Santa Barbara counties. Most of the historic locations, including over documented 40 occurrences, have been lost primarily as a result of agricultural development and grazing (Taylor and Davilla 1989). California jewel flower has sometimes been placed in a separate genus (Stanfordia) based on the compression of the fruit and the seeds (Buck 1993; Rollins 1993). Most current California references use the name Caulanthus californicus (Anonymous 2008a, 2008b; Buck 1993).

Participating Institutions
Updates
  • 09/03/2020
  • Orthodox Seed Banking

In 2017, the Santa Barbara Botanic Garden conducted surveys and collected seeds from Caulanthus californicus for long-term preservation in their conservation seed bank.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden holds 4 accessions of Caulanthus californicus in orthodox seed collection. There are as many as 17963 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, University of California Botanical Garden holds 1 accessions of Caulanthus californicus in orthodox seed collection. We are uncertain as to how many total seeds are in this collection.

  • 09/01/2020
  • Orthodox Seed Banking

Based on an September 2020 extract of the California Plant Rescue Database, California Botanic Garden holds 1 accessions of Caulanthus californicus in orthodox seed collection. There are as many as 193 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden has collected 4 seed accessions of Caulanthus californicus from 4 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 54 maternal plants

  • 08/05/2020
  • Seed Collection

Based on an August 2020 extract of the California Plant Rescue Database, University of California Botanical Garden has collected 1 seed accessions of Caulanthus californicus from 1 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass an unknown number of maternal plants

Heather Schneider
  • 05/22/2018

In 2017, the Santa Barbara Botanic Garden conducted surveys and collected seeds from Caulanthus californicus for long-term preservation in their conservation seed bank.

Nature Serve Biotics
  • 05/02/2017

Approximately 20 occurrences are extant; at least 35 have been extirpated. Threatened by agriculture, urbanization, energy development, and grazing.

Dieter Wilken
  • 01/01/2010

Competition from exotic annual grasses Intensive grazing Potential agricultural development Random loss of small, local populations

Dieter Wilken
  • 01/01/2010

The number of plants varies from year to year, depending on rainfall in the preceding winter. During drought years, few if any plants may be present (Twisselmann 1967; Williams et al. 1998). About 35 extant populations were estimated to be extant in the mid 1990s. In some areas many populations were found in close proximity, with numbers of individuals ranging from as few as 3 to over 2,000 in others.

Dieter Wilken
  • 01/01/2010

Populations on public lands in Fresno County are managed by the Bureau of Land Management, Hollister District. Populations in the Carrizo Plain National Monument are managed by the Bureau of Land Management, Bakersfield District. Experimental populations in the upper Cuyama Valley, Santa Barbara County, were located on lands managed by the Los Padres National Forest. Other populations on private lands are presumably managed by the land holders.

Dieter Wilken
  • 01/01/2010

A long-term, experimental study to determine critical factors fostering establishment, including appropriate number of seeds, appropriate seed treatment prior to planting, and minimum requirements for supplemental watering.

Dieter Wilken
  • 01/01/2010

Development of a conservation seed bank Development of a propagation protocol to be applied to in situ conditions

MORE

Be the first to post an update!

Photos
Nomenclature
Taxon Caulanthus californicus
Authority (S. Watson) Payson
Family Brassicaceae
CPC Number 842
ITIS 23077
USDA STCA23
Common Names California caulanthus | California Jewelflower | St. Francis cabbage
Associated Scientific Names Caulanthus californicus | Stanfordia californica | Streptanthus californicus
Distribution Foothills and valleys of the southwestern San Joaquin Valley, California.
State Rank
State State Rank
California S1
Habitat

Typical habitats include flats, alluvial fans, and gentle slopes with sandy to gravelly soils (Taylor 1983). Typical plant communities include open grasslands and shrublands dominated by salt-bush (Atriplex) or Mormon tea (Ephedra).

Ecological Relationships

Some large and vigorous populations in valley bottoms appear associated with kangaroo rat colonies. Although plants may experience herbivory and reduction in fruit production from this association, populations as a whole may benefit as a result of reduced competition (Cypher 1994). Flowers apparently require pollination by insects, because plants grown under insect-free conditions do not set significant numbers of fruits or seeds (Mazer and Hendrickson 1993). Seeds do not readily germinate unless they have been exposed to cold temperatures and scarification. Ad hoc observations of varying population size over years or colonization of abandoned fields suggest the presence of a seed bank in some populations. (Cypher 1994; Williams et al. 1998).

Pollinators
Common Name Name in Text Association Type Source InteractionID

Donate to CPC to Save this Species

Fall fundraising drive has begun! We're looking for 2,500 people to protect our planet. With you by our side, we will build a future where people live in harmony with nature. Come help and become a CPC donor today.

Donate Today