That is very considerate of you to try and avoid plants poisonous to livestock. There are a number of ornamentals and flowers that are toxic to animals, including rhododendron, foxglove, oleander, Japanese yew, bleeding heart, lilies and jimsonweed. This is not a complete list by any means.
For more plants that are toxic to horses, you can visit our eXtension Pasture Management Learning Lesson at http://campus.extension.org/mod/book/view.php?id=131, or for an even more complete list, visit Cornell’s poisonous plant website at http://www.ansci.cornell.edu/plants/php/plants.php?action=indiv&byname=c....
