Search / Plant Profile / Calycadenia villosa

Plant Profile

Dwarf Rosinweed (Calycadenia villosa)

As a member of the Aster family, C. villosa has both disk and ray flowers. Photo Credit: Dieter Wilken

Global Rank: G3 - Vulnerable
Legal Status: N/A
Family: Asteraceae
State: CA
Nature Serve ID: 158655
Lifeform: Forb/herb
Date Inducted in National Collection: 05/01/1999

Description:

Dwarf Calycadenia is a summer-flowering annual up to 30 cm tall, with a basal rosette of many, grayish, simple leaves. Each plant can produce from 1 to 15 heads with 1-4 white to pinkish ray flowers and 10 to 15 disk flowers. Most populations are composed of plants with a single, simple to distally branched stem, but a few in San Luis Obispo County are shorter and have several ascending to spreading stems from the base. Prior to 1999, only 2 localities were documented, collectively composed of less than 1000 plants. Other reports were based on mis-identifications. Surveys conducted by the Santa Barbara Botanic Garden, however, have revealed at least 83 occurrences, all restricted to southern Monterey and northern San Luis Obispo counties. Most documented occurrences occur on Fort Hunter Liggett in Monterey County, California.

Where is Dwarf Rosinweed (Calycadenia villosa) located in the wild?

Habitat:

Open sites or barren areas composed of sandy to fine-gravelly clay soils, often in oak savanna and grasslands, but sometimes on talus or rock outcrops in chaparral. Common associates include Lasthenia californica, Linanthus liniflorus, Micropus californicus, Lotus purshianus, and other spring-flowering annual dicots.

Distribution:

Eastern slope of the Santa Lucia Mountains and the La Panza Range, from southern Monterey to northern San Luis Obispo counties, California.

States & Provinces:

Dwarf Rosinweed can be found in California

Which CPC Partners conserve Dwarf Rosinweed (Calycadenia villosa)?

Santa Barbara Botanic Garden

Not Sponsored

Conservation Actions

Assigned 06/09/17

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 2 accessions of Calycadenia villosa in orthodox seed collection. There are as many as 200 seeds of this species in their collection - although some may have been used for curation testing or sent to back up.

09/01/2020

Systematic relationships and status of the two growth forms are being studied by Bruce Baldwin, Jepson Herbarium, University of California at Berkeley. (Baldwin 1993)

08/05/2020

Based on an August 2020 extract of the California Plant Rescue Database, Santa Barbara Botanic Garden has collected 2 seed accessions of Calycadenia villosa from 2 plant occurrences listed in the California Natural Diversity Database. These collections together emcompass 85 maternal plants

Nature Serve Biotics

05/02/2017

Endemic to California, Calycadenia villosa is known from sixteen occurrences in Monterey and San Luis Obispo Counties, eight of which are recently confirmed. Seven of these occurrences are on Ft. Hunter-Liggett lands with little or no protection. Threats are urbanization, vehicle activity, and non-native plants.

Dieter Wilken, Ph.D.

01/01/2010

Alteration of habitat through development, road construction, and military training activities. Competition from noxious weeds. Loss of reproductive plants during human-cause fires.

Dieter Wilken, Ph.D.

01/01/2010

At least 82 sites have been documented, of which about 70 have from 10 to 1,000 individuals in an average year. Another 10 occurrences support populations usually greater than 1,000 each. Censuses of plants have varied annually resulting from a positive correlation between winter precipitation and population size.

Dieter Wilken, Ph.D.

01/01/2010

Systematic relationships and status of the two growth forms are being studied by Bruce Baldwin, Jepson Herbarium, University of California at Berkeley. (Baldwin 1993)

Dieter Wilken, Ph.D.

01/01/2010

Most populations occur on Fort Hunter Liggett, a military training facility that is managed by the US Army. At least one population occurs on Camp Roberts, a military training facility managed by the California National Guard. Currently, no special conservation attention is given to occurrences on Fort Hunter Liggett, but the population on Camp Roberts is protected partly by restricted access. At least one population occurs on land managed by Los Padres National Forest, and is protected partly by an elevated pipe barrier, coincident with one of two sites of the federally threatened Camatta Canyon amole (Chlorogalum purpureum var. reductum). (Wilken 2000)

Dieter Wilken, Ph.D.

01/01/2010

Genetic analyses within and among populations. Studies of the breeding system, seed dormancy and germination requirements, and other variables important to understanding ecological distribution.

Dieter Wilken, Ph.D.

01/01/2010

Seed collections representing the entire geographic distribution.