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 complex 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 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, botanical, 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 -18o 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 banking rare and endangered species, the Seed Program provides genetic material from its seed bank collection through it's Index Seminum program published on the Garden's website or in the form of tissue samples from the Garden's living display collection. All seed collections made for use in RSA's Horticulture programs are processed, tested, stored, and distributed through the Seed Program.

Definition of Collections

The seed bank collections stored at RSABG, categorized by their quality, 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 and seed exchange 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.

(Undocumented seed collections are not included in the Gardens web page seed list)


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 existence of ex-situ (off site) germplasm collections:
Help to conserve material for future restoration and reintroduction projects, preserve population level genetic information, and serve as a resource for ecological, physiological, systematics and taxonomic research.
Well documented collections at Botanic Gardens serve as a relatively inexpensive and easily accessed source for research material thereby protecting natural populations from the potential negative impacts of collecting and sampling.
Seeds in storage programs will ultimately help us to better understand the potential and the limitations of seed storage as a conservation tool.
Germplasm collections incorporated into living collections and interpretive displays at botanic gardens facilitate opportunities for increased public education and greater appreciation for conservation of a regions natural biotic heritage.

None-the-less, as valuable as these collections are, it needs to be recognized by all participants working to conserve habitats and species that ex-situ conservation collections merely serve as one component of an integrated conservation strategy utilized to protect against plant population degradation and to prevent extinction. Government, business, and community efforts to preserve and restore plant populations in their natural habitat should always be the first and highest priority.

Seed Storage Practices at RSABG

After seeds are cleaned, inspected, counted and packaged they are placed open for a minimum of three weeks to equilibrate at 20° C ( 68 ° F ) and 13-15% RH (using silica gel desiccant). The storage containers are then sealed and placed into chest style freezer units 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 distributed 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 USDA National Center for Genetic Resource Preservation in Fort Collins, CO.

Many threatened and endangered collections 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

Standard testing procedure used at RSABG is described below. This procedure is followed for all initial viability tests unless seed pre-treatment, alternative temperature regimes, or procedural requirements are known to be, or assumed to be necessary to initiate germination.
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

Images below (left to right): Rabbitbrush and buckwheat in autumn, Photo ©2006 Michael E. Gordon / www.mgordonphotography.com. Results of viability tests on rabbitbrush seed in cold storage vs. room storage conditions over a two year period.

Germination References for California Native Plants

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