United States Department of Agriculture This excellent site includes Canadian distribution and shows pictures and range maps. It is searchable by scientific or common name. I find it useful to search by genus and compare subspecies and their occurrence in Ontario.
Walter Muma provides multiple photos of the same species to help with identification. Good keys for sorting out Asters and Goldenrod. Links to other information about native plants in Ontario
Flora of North America
A lot of technical information, but good keys and illustrations. I have used this site to key out species of sedge - the detailed drawings are excellent.
PROPAGATING FROM SEED
Ontario Rock Garden and Hardy Plant Society
An excellent germination guide for all sorts of native and non-native seeds. The Germination Guide is in the top menu.
Tom Clothier Garden Walk and Talk
Another great resource for germinating all kinds of seeds. Check out the gardening articles too.
ORGANIZATIONS and SOCIETIES
North American Rock Garden Society (NARGS)Photos. articles, special events, resources and one of the best annual seed exchanges on the continent. Local chapters exist in your region too.
Ontario Rock Garden and Hardy Plant Society (ORGHPS)
Active group of gardeners that organize monthly speakers, tours, workshops as well as a seed exchange of hardy species. Monthly meeting sin Toronto and a monthly journal. The website is excellent.
American Penstemon Society A group dedicated to the study and cultivation of the 100s of species of... Penstemons. A bit specialized, but a fascinating group of North American plants. Annual seed exchange and trips. http://www.apsdev.org/