This new book updates and amends Gentry's Rio Mayo Plants. Undertaken with Gentry's support and participation before his death in 1993, it reproduces the original text, which appears here with annotations, and contains information on over 2,800 taxa - more than twice the 1,200 species first described by Gentry. The annotated list of plants includes information on distribution, habitat, appearance, common names, and indigenous uses. A new introduction provides historical background and a review of geography and vegetation. It also describes changes to the land and river wrought by agricultural development, expanded grazing, and lumbering.