410 SYSTEMATIC BOTANY [Volume 22 Systematzc Botany (1997),22(2) pp.410-411 © Copyright 1997 by the American Society of Plant TaxonomIsts groupings recognized. There is no ranking of communities above the series. Some communities are treated as "habitats" or as "unique stands," rather than being grouped into associa- tions or series. The CNPS system includes communities composed of native species, introduced species (a very signifi- cant part of the California flora), and various mixhrres. A Manual of California Vegetation is the product of the committee's efforts. It is a work in progress that is, unfortunately, somewhat overtitled. Perhaps a more realis- tic title should be "A Preliminary Inventory of Some California Plant Communities" which would indicate that much work is left to do. At this point the Manual is incomplete. Only associations for which the desired level of detail was available to the committee are listed. As a result, many known associations are not listed or must be shoehorned into one of those listed in the Manual. Because much of the state's vegetation has never been subjected to the level of scrutiny needed for the CNPS classification system, the gaps are many and glaring. Dlrring spring trips with ollY field botany class V L. Holland and I tried out the CNPS system. Unfortunately it was impossible to place many familiar associations with any described in the Manual. The committee plans fuhrre editions to fill gaps in coverage of this volume. I suspect that an adequately thorough treatment of the state's vegetation will require several volumes. There are practical problems beyond incompleteness in applying the CNPS classification scheme. I am not con- vinced that the floristically based assemblages recognized in the CNPS treatment are the most practical entities for describing California's vegetation, especially when di- vorced from a higher level classification. Communities often do not align themselves into neat associations. Within a particular chaparral or grassland stand, for instance, it is very common to see species composition and dominance subtly shifting from site to site in response to local variation in A Manual of California Vegetation by John O. Sawyer and Todd Keeler-Wolf. 1995. 471 pp. 32 color plates. ISBN 0-943460-26-3 (paper) $39.00. Sacramento: California Na- tive Plant Society. The California Native Plant Society (CNPS) is an organi- zation of amateurs and professionals dedicated to the preservation of California's native flora. The CNPS has provided leadership in inventorying and evaluating the status of the rare and endangered plants of the state and in educating the public about the importance of native species. As knowledge of the threats to the state's plant life has increased, there has been a growing awareness at various levels in the CNPS that more than individual native taxa are in danger. Many of the plant communities of the state are threatened with obliteration or irreversible modification. In 1991 a CNPS committee was established to inventory and evaluate the plant communities of California with goals of (1) establishing a consistent, quantifiable classifica- tion of all communities of the state, and (2) making possible legal protection of rare communities by recogniz- ing their uniqueness and threats to their existence. This is an ambitious undertaking. California's vegetation is remarkably diverse and variable in physical characteristics and species composition, reflecting the state's ecological diversity and complex history. In the view of committee members, the several previously proposed systems of classification for the state's vegetation had shortcomings and conflicts, and none consistently recognized communities at the level of detail that the CNPS committee considered desirable. The CNPS committee determined that the appropriate classification should be based on floristically based assem- blages termed series (groups of associations, recognized from field analysis of one or more stands). The system is an essentially non-hierarchical classification with only low-level