In 1993, the Jepson Herbarium completed The Jepson Manual; Higher Plants of California. Since then, The Jepson Manual has become the authoritative floristic reference for the state and is used by professional botanists, agency personnel, environmental consultants, conservation planners, teachers, and students as a conservation tool and a primary resource for plant identification.

Although the Manual was published only 10 years ago, it is rapidly becoming out-of-date as a result of the phenomenal progress in plant systematics. Some significant taxonomic changes have already been made and others are on the horizon; it is estimated that 57% of the families in the 1993 edition of The Jepson Manual will require substantial revision.

At this time, revised taxonomic treatments are not available for most groups and therefore botanists are forced to use outdated and incomplete references when identifying plants. Because accurate plant identification is essential to guide responsible land use and conservation decisions, the revision of outdated treatments, to reflect new insights on plant relationships, diversity and distribution, is an urgent priority.

The Jepson Herbarium has initiated a five-year project (2003–2008) to produce a scientifically revised Jepson Manual. The Second Edition will provide revised treatments for all taxa in the 1993 edition of the Manual and include new treatments for taxa that have been added to the flora of the state since 1993 (either as new to science or as newly reported for California).

To improve the utility of this work for conservation biology and ecology, two substantial operational changes will be incorporated in the Second Edition: (1) where possible, only monophyletic groups (evolutionary lineages) will be recognized, and (2) taxa that can be identified only by fine-scale characteristics will be recognized. These changes, along with others (such as inclusion of flowering times) will distinguish the Second Edition from the 1993 Manual.

Marking a new era in California floristics, the Second Edition of The Jepson Manual will be integrated with a variety of electronic resources, available through the Jepson Online Interchange. The electronic resources are projected to include interactive keys, improved distribution maps with georeferenced localities, searchable character and ecological databases, synonymy reference tables, phylogenetic trees, links to photographs and illustrations, and other resources designed to complement and enhance the printed book. Together, The Jepson Manual and the Online Interchange will be the most comprehensive, scientifically accurate sources of information on the California Flora.

Completion of the Second Edition will depend on the generosity of donors who share the Herbarium's interest in pursuing Dr. Jepson's vision of documenting and preserving California's environmental and botanical riches.

More information on the production of the Second Edition (large pdf file).

More information on fundraising programs and donor opportunities.

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