Cornell University Poisonous Plants Home Page
http://www.ansci.cornell.edu/plants/index.html
National Animal Poison Control Center
http://www.napcc.aspca.org/
Plants and Your Cat (Cat Fanciers Assoc.)
http://www.cfainc.org/articles/plants.html
Plants Toxic to Animals (Univ. of Illinois) http://www.library.uiuc.edu/vex/vetdocs/toxic.htm
Indiana Plants Poisonous to Livestock and Pets (Purdue University) http://www.vet.purdue.edu/depts/addl/toxic/bytox1.htm
Lists plants alphabetically, by toxicity rating, by species, and by botanical type along with a picture index.