Herbaceous plants fit roughly into 3 categories, namely annuals, biennials, and perennials.
Annuals are plants that complete their growing cycle in a single year or season. They germinate, grow vegetatively, flower, set seed, and then die. Many plants grown as annuals in temperate climates may actually be "tropical perennials".
Biennials are similar to annuals, except that they do their vegetative growing one year, then flower, set seed, and die the following year.
Perennials are plants that live year after year, going through regular cycles of vegetative growth, flowering, setting seed, and then returning to vegetative growth (usually with periods of dormancy in between). Woody plants such as trees, shrubs, and vines are also perennials, but are not addressed in this volume.
The approach of this book is to discuss the planting and maintenance of individual herbaceous plants. Over time, there may be many thousands of entries.