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"Poisonous" does not mean deadly. Some manifestations of toxicity are subtle. The dose, as always, determines if a plant is safe source of nutrients or a toxic hazard.

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BRIEF: Which poisonous plants are in the Bay area of California?

Which of these poisonous plants are in the Bay Area of California, and which would be the best book for information in this area?


Which of what poisonous plants? Poisonous to livestock, people, dogs? Naturalized, native or ornamentals? In the east Bay, I would guess that oleander (Nerium oleander), yew (Taxus spp.), grounsel (Senecio spp.) and fiddleneck (Amsinckia intermedia) would be the most threatening things your sheep might run into and if eaten by dogs or humans, they wouldn't be too nice either. People still plant castor bean as an ornamental out there, too, and you don't get much more poisonous than that! I grew up in Sacaramento and was on the UCDavis faculty for a long time, so I know some of the botany of the area. Poisonous Plants of California by Fuller and McClintock is the best book.