This is where my Peterson's Field Guide to my region's native plants has been invaluable to me! Thanks to adopting a sulcata I know more about plants today than I ever wanted to know! LOL
Run into a library, a Barnes & Noble, or other book store & see if you can find a field guide for your region to ID the plant.
Or check out these URLs & see if you can find it:
http://www.library.uiuc.edu/vex/vetdocs/toxic.htm
http://aggie-horticulture.tamu.edu/plantanswers/publications/poison/poison.html
http://envhort.ucdavis.edu/ce/king/PoisPlant/Tox-COM.htm
http://envhort.ucdavis.edu/ce/king/PoisPlant/SAFE-COM.htm
http://www.turtlestuff.com/ingredients.html
http://www.weedalert.com/cgi-bin/weedalerts.cgi?region=so
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PHRatz