- Colorado Flora Eastern Slope: A Field Guide to the Vascular Plants, 4th edition, and: Colorado Flora Western Slope: A Field Guide to the Vascular Plants, 4th edition by William A. Weber and Ronald C. Wittmann
Every botanist studying Colorado plants should have these books. They fill an important niche between a state flora that is complete but too bulky to easily take to the field and most field guides that cover only the common and showy plants. These field guides include keys to the entire flora but lack morphological descriptions. Nonetheless, comments about habitats, abundance, distribution, similarities to closely related taxa, native or alien status, taxonomic notes, synonyms, and various interesting tidbits are included after the species names in the keys. Included are more than 100 pages of line drawings at the end of each field guide. By dividing the state into 2 sections, the size of each field guide and the length of the keys remain manageable for field use. As the names imply, the western slope guide covers everything west of the continental divide, and the eastern slope guide covers everything east of the divide. Plants in the Colorado high country are fairly well covered by either field guide.
These 2 guides had their beginning in 1953 with publication of the Handbook of Plants of the Colorado Front Range. This handbook was followed in 1967 by the Rocky Mountain Flora. The first edition of Colorado Flora Western Slope was published in 1987, with Colorado Flora Eastern Slope published in 1990.
These guides follow the same format as previous editions, but the nomenclature has been updated. For example, all Cleome in Colorado are now Peritoma. Synonyms and common names are included in the index so you can still locate a given species in the field guide even if you know only the old name or the common name, but not the new scientific name. A new and excellent key to Botrychium is included, contributed by Donald Farrar and Steve Popovich.
You will find some nomenclature in these field guides that is different from most other guides and floras, including the Flora of North America volumes. For instance, the genus Euphorbia is absent from the guides. Species called Euphorbia elsewhere are included instead in either Chamaesyce, which is often done in other floras, Agaloma, Poinsettia, or Tithymalus. The family Caryophyllaceae is divided in two with the chickweeds and their relatives being placed in the Alsinaceae. These treatments are expressions of the authors’ taxonomic opinions. Only time and further study will determine if their interpretations are right. In the meantime, do not let this deter you from buying and using these excellent field guides. [End Page 115]
Charlie McDonald is Chairman, New Mexico Rare Plant Technical Council and retired Regional Botanist, USDA Forest Service, Southwestern Region.