Arizona Native Plant Society The Arizona Native Plant Society is a statewide nonprofit organization devoted to Arizona's native plants. The site has information on rare native plants, invasive plants, conservation and plant laws. there's also a link to another site the society maintains, called Grow Native: Don’t Plant a Pest public education campaign. there are several links to other sites of interest to high desert gardeners as well.
Arizona Range Grasses Their description, morphology and growth patterns.
Arizona Weeds, An Illustrated Guide by Kittie F. Parker.
Baja Arizona Sustainable Agriculture Baja Arizona Sustainable Agriculture, (Baja AZ), is a 501c3 non-profit organization working to increase local sustainable food production and marketing in southern Arizona.
Biological Treatments for Pests in the Garden Images of garden pests and suggestions of biological treatments listed in order of effectiveness. Beneficial insects and images are on another page in alphabetical order. There's also a page of faqs on insects.
Botanical.com has a great index of herbs and other plants. There's also a smaller index of poisonous plants, some conversion tables and recipes. Includes the hypertext version of "A Modern Herbal",written in 1931 by Mrs. M. Grieve.