A Modern Herbal: Index of more than 800 varieties of herbs and plants, word search of the text, recipes, and an index of poisonous plants.
Botany Encyclopedia of Plants.: Provides general description of plants, various methods of cultivation, soil and temperature requirements, pruning.
Lapshin's Succulent Encyclopedia: Photos of succulents of numerous families.
Metropolitan Plant Encyclopedia: Consists of a series of comprehensive pages on the plants of the New York metropolitan region.
Virtual Palm Encyclopedia: History, horticulture, pests and diseases, conservation, photographs, and references.