Weed Control for Home Lawn & Garden Help with anthurium! It was looking really good until few weeks ago and suddently all the flowers are turning brown, crispy and dying (i have removed them) and there are suspicious spots Not all plants are as harmless as they look. Some of the most common houseplants and flowers can actually be toxic to dogs and cats. From lilies and aloe vera to pothos Dieffenbachia is Toxic Pet lovers, beware Did you know? Dieffenbachia contains a toxic sap What makes it toxic? Contains calcium oxalate crystals