National Collection of Imperiled Plants

CPC National Collection Plant Profile

Photographer:

Dieter Wilken

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CPC National Collection Plant Profile

Calycadenia villosa

Family:	Asteraceae
Common Names:	dwarf calycadenia, dwarf rosin-weed
Author:	DC.
Growth Habit:	Forb/herb
CPC Number:	8101

Distribution
Protection
Conservation
References

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Photographer: Dieter Wilken
dwilken[at]sbbg.org

Calycadenia villosa is Not Sponsored

Primary custodian for this plant in the CPC National Collection of Endangered Plants is:

Santa Barbara Botanic Garden

Dieter Wilken, Ph.D. contributed to this Plant Profile.

Calycadenia villosa

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.

Distribution & Occurrence

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State Range

California

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.

Number Left

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.

Protection

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Global Rank:	G2	8/25/2003	Guide to Global Ranks
Federal Status:			Guide to Federal Status
Recovery Plan:	No

State/Area Protection

	State/Area	Rank	Status	Date
	California	S2.1

Conservation, Ecology & Research

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Ecological Relationships

Calycadenia villosa is restricted to sites free from competition with other plants. Populations often occur on apparently barren sites that do not support alien plants such as yellow star thistle and Mediterranean grasses, which often surround such sites. Most populations are characterized by low densities, often in patches but sometimes with widely scattered plants spaced up to 1 meter apart. Flowering takes place from late June to early October.

Threats

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

Current Research Summary

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

Current Management Summary

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)

Research Management Needs

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

Ex Situ Needs

Seed collections representing the entire geographic distribution.

References

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Books (Single Authors)

Skinner, M.W.; Pavlik, B.M. 1997. Inventory of rare and endangered vascular plants of California: Electronic Inventory Update of 1994, 5th edition. Sacramento: California Native Plant Society.

Books (Sections)

Kartesz, J.T. 1999. A synonymized checklist of the vascular flora of the U.S., Canada, and Greenland. In: Kartesz, J.T.; Meacham, C.A., editors. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden. Chapel Hill, NC.

Books (Edited Volumes)

James C. Hickman, Editor. 1993 The Jepson manual: Higher plants of California. Berkeley: University of California Press. 1400p.

Electronic Sources

(2002). Hawaiian Native Plant Genera. � Gerald D. Carr, University of Hawaii Botany Department. http://www.botany.hawaii.edu/faculty/carr/natives.htm. Accessed: 2002.

Journal Articles

Baldwin, B.G. 1993. Molecular phylogenetics of Calycadenia (Compositae) based on its sequences of nuclear ribosomal DNA: chromosomal and molecular evolution reexamined. American Journal of Botany. 80: 222-238.

Reports

Wilken, D. 2000. Rare plant survey at Fort Hunter Liggett: Technical Report No. 2. Santa Barbara, CA: Santa Barbara Botanic Garden. p.35 + appendices.

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This profile was updated on 3/4/2010