Your email address will not be published. The trap lies in the palatability of this flower, and the fact that it grows in the early spring before even grass grows – leaving the only option for the cattle. Not only flowers but all parts of this plant are toxic. This is not a toxic reaction. 7 of the World's Deadliest Plants Water Hemlock (Cicuta maculata) Deadly Nightshade (Atropa belladonna) White Snakeroot (Ageratina altissima) Castor Bean (Ricinus communis) Rosary Pea (Abrus precatorius) Oleander (Nerium oleander) Tobacco (Nicotiana tabacum). They are equally poisonous for humans as well for cats and dogs, as mentioned by ASPCA on its website. Pruning should be done in the warmer months, once all the flowers have properly bloomed. Besides flowers, the stems, seeds, leaves, and any part above the ground is poisonous. A guide to identifying the most dangerous plants in the United States that are poisonous to humans. Full to partial sun. Poisoning happens because this plant resembles many other plants from several aspects. The wandering jew does not necessarily cause a toxic like reaction in dogs, but more of an allergic reaction. It’s the poisonous Japanese flower as well. However, cats and dogs do love the taste of the spider plant, and sometimes they will eat enough to make them sick. //