The mission of the Garden is to make significant contributions to the appreciation, enjoyment, conservation, understanding, and thoughtful utilization of California's natural botanical heritage.

This mission was enhanced in November, 1994 when new seed processing and storage facilities were established through the generous support of the Fletcher Jones Foundation. The Fletcher Jones Education Center for the Preservation of Biodiversity includes cold storage for seeds, climate controlled growth chambers that facilitate germination studies and graduate program research, seed processing equipment and ample laboratory space.

The primary function of RSABG's Seed Conservation Program is the curation and management of the Garden's extensive seed collection. The collection is comprised of over 3,000 accessions representing more than 1,600 California native plant species and cultivars. These collections serve a diverse community in the conservation, research, education, and horticultural fields.

Following guidelines set by the International Board for Plant Genetic Resources, Center for Plant Conservation (CPC), and in consultation with the USDA National Center for Genetic Resource Preservation, the Garden provides low humidity and low temperature long-term seed storage for the preservation of plant genetic resources. Facilities presently available include -18° Centigrade freezers as well as all of the equipment necessary to appropriately process and store seed collections.

Through a Memorandum of Understanding with the State of California Department of Fish and Game and the U.S. Fish and Wildlife Service, the Garden is authorized and regularly utilized as the principle repository for germplasm collections of rare, threatened, and endangered California native plant species.

In 1985, the Garden became a charter member of the Center for Plant Conservation (CPC). One of thirty-four gardens and arboreta nationally, RSABG helps to maintain a national collection of some of the most critically endangered plant species. Coordinated by the CPC, regional participating institutions endeavor to place critically endangered species into cultivation and/or maintain seed collections of these plants in long-term cold storage. In addition to preserving seeds of rare, threatened, and endangered species, the Seed Conservation Program provides seeds as well as tissue samples from the Garden's living display collection for research, display, and educational use at other institutions.

Seed Storage and Conservation 

As various human impacts on the environment continue to reduce the abundance and distribution of many plant species even to the point of extinction, seed banking and other related ex-situ conservation strategies are becoming increasingly valuable and necessary conservation tools. 

The benefits of ex-situ (off site) seed and living plant collections:
1.       Ex-situ collections conserve material for habitat restoration as well as for endangered species recovery projects.
2.       High quality genetically representative germplasm collections can serve as a fairly inexpensive insurance policy protecting our most threatened plants and their associated species from extinction.
3.       Well documented collections at Botanic Gardens (plants, seeds, pollen, tissue samples) serve as a relatively inexpensive and easily accessed source of material for research use thereby protecting natural populations from the potential negative impacts of collecting and sampling.
4.       Seed banks will ultimately help us to better understand both the potential and the limitations of seed storage as a conservation tool.
5.       Seed and living plant collections help us to better understand horticultural requirements necessary to propagate and recover endangered species and their habitats.
6.       Lastly and most importantly, off site germplasm incorporated into living collections and interpretive displays at botanic gardens, universities, parks, and museums facilitate opportunities for increased public education and greater appreciation for our natural biotic heritage and processes.

Seed images by John Macdonald   http://www.hazmac.biz/rsabghome.html

Seed Storage Practices at RSABG 

• Definition of Collections

The seed bank collections stored at RSABG, categorized by their purpose and ultimate use, are defined as follows: 
1.       Documented "conservation" collections - consisting of rare, gene pool representative germplasm collections that primarily serve to prevent extinction and as a source material for conservation research and restoration.
2.       Documented collections - collections designated to serve general research, education and horticultural programs at RSABG as well as at other institutions through the Garden's electronic website Index Seminum program. Samples of wild collected State or Federally listed plant species are not released without approval from the appropriate regulatory authorities.
3.       Undocumented collections - collections of unknown wild parentage, from plants cultivated and harvested at RSABG on a regular basis, that serve horticultural, educational, and gift shop programs.

• Processing Seed Collections

After seed collections are processed and inspected for purity and viability, they are placed for a minimum of three weeks to equilibrate at 20° C ( 68 ° F ) and 13-15% RH (using silica gel desiccant). The collections are weighed, counted and packaged, then the storage containers are sealed and placed into storage at -18°C (0°F). Plant species listed in the California Native Plant Society's (CNPS) "Inventory of Rare and Endangered Plants" are stored in heat sealable type 321 foil/plastic laminate storage bags manufactured by Barrier Foil Inc. Manchester England. Seed collections of more common species are stored in double sealed plastic bottles. Rare and endangered species accessions (CNPS 1B) with more than 500 seeds are packaged into three storage units: 20% "active" for testing and distribution; 40% "base" for long term undisturbed storage; 40% (up to 3,000 seeds) "back-up" for storage at the USDA National Center for Genetic Resource Preservation in Fort Collins, CO. Many collections of highly threatened and endangered species are maintained along maternal lines where each individual plant sampled within a population has its seed packaged separately. This collection and storage practice allows for better control of genetic representation in seed regeneration and restoration projects.

• Viability Testing

During processing, small samples of light weight seed are separated with a seed blower and then dissected under magnification and checked for healthy endosperm and/or embryo tissue. Most seed collections can be processed to achieve a minimum of 95% filled, sound, seed.

• Germination Testing

The standard testing procedure used at RSABG is described below. This procedure is followed for all germination tests unless seed pre-treatment, alternative temperature, light, or procedural requirements are known to be necessary.

•        Procedure: 0.5% agar solution on sterilized styrene examination plates.
•        Std. test lot size: 25-100 seeds
•        Environment: 11 hrs. light @ 20° C / 13 hrs. dark @ 12° C

All incoming seed collections are tested to document either the level of dormancy or seedling vigor in non-dormant seeds. Follow up germination tests to monitor storage tolerance are performed as time and opportunity allow with priority given to funded conservation seed collections.

• Seed Longevity in Storage

The length of time that seeds can maintain viability varies greatly depending on many factors including the particular species, the storage environment, and the quality of the seed. For more information on this subject see Seed Storage Guidelines.

For many plant species controlled storage can greatly increase longevity. The graph below compares seed viability over time when rabbitbrush seed is stored at room conditions vs. being dried to low moisture content and maintained in a frozen state. In 2009, after 10 years in storage the test was repeated and germination was 84% with seedlings producing healthy, vigorous roots and cotyledons.

Germination References for California Native Plants

While there are many references on seed germination, the first three references in the short list below are specific to germinating seeds of wild collected plants. Seeds of many wild plant species often have complex dormancy that allows them to survive in their natural environment. This dormancy inhibits germination, often for decades and sometimes for centuries, until changes in the local environmental conditions, seed physiology, or seed chemistry occur, shifting the seed from a state of dormancy to one of germination. The last reference addresses seed dormancy in great depth and contains a wealth of additional references on this topic.

•        Emery, Dara E. 1988. "Seed Propagation of Native California Plants." Santa Barbara Botanic Garden.
•        Young & Young. 1986. "Collecting, Processing and Germinating Seeds of Wildland Plants." Timber Press.
•        Young & Young. 1992. "Seeds of Woody Plants in North America." Dioscorides Press.
•        Carol C. & Jerry M. Baskin. 1998. "Seeds: Ecology, Biogeography, and Evolution of Dormancy and Germination." Academic Press.

Seed Conservation Program Staff and RSA Start Date

•        Michael Wall, Seed Conservation Program Manager - 1990
•        Genevieve Arnold, Seed and Research Collections Technician - 2000
•        Kit Tournay, Volunteer - 1980
•        Barbara Stanford, Volunteer - 1990
•        Norma Standard, Volunteer - 1996
•        Jim Herschberg, Volunteer - 1997
•        Ed James, Volunteer - 1999
•        Marge Hammond, Volunteer - 2001
•        John Macdonald, Volunteer - 2001
•        Vic Andresen, Volunteer – 2007