Plant Science

AgNIC - Agriculture Network Information Center
Biodiversity Heritage Library: A collection of digitized taxonomic literature from a consortium of natural history and botanical libraries.
Botanicus Digital Library: A freely accessible, Web-based encyclopedia of digitized historic botanical literature from the Missouri Botanical Garden Library.
Global Biodiversity Information Facility: Integrated Taxonomic Information System (ITIS) for plants
Plant Gene Resources of Canada

Agriculture and Agri-Food Canada
Atlantic Food and Horticulture Research Centre
Natural Resources Conservation Service
United States Department of Agriculture - Plant Health

American Society of Plant Biologists
Botanical Society of America
Botanic Gardens Conservation International
Canadian Phytopathological Society
Canadian Society of Plant Biologists (CSPB)
Canadian Weed Science Society (CWSS)
Food and Agriculture Organization of the United Nations (FAO)

Distribution Maps of Plant Diseases
Invasive and Exotic Species of North America

CalPhotos
Images from the Biodiversity Heritage Library
Plant Image Collection
Plants Gallery