Botany.net

Complete Gardener Encyclopedia

Encyclopedia of Botany
plant taxonomy and links to botanical gardens and associations

Herbal Encyclopedia

Mansfeld's World Database of Agricultural and Horticultural Crops
(IPG-Gatersleben)

A Modern Herbal
A hyper-text version of A Modern Herbal, 1931, by Mrs. M. Grieve. Over 800 varieties of medicinal, culinary, and cosmetic herbs, including economic properties, cultivation and folk-lore

Weeds - Plant Pathology Internet Guide Book (PPIGB)

Plant Delight Nursery

Weed Science Society in America

FORIS - FAO Forestry Information System