You may already know common plants, like oleander or holly, that are harmful to dogs and cats, but if you're thinking of buying a plant and aren't sure if it is safe for your pet, the ASPCA's searchable index can help. You can search the index for specific plants or filter the list by pet types (dog, cat and so on). Click through to the plant's profile to learn what qualities make it toxic, which type of pets it is toxic to, and reactions your pet may have to the plant. For this index, toxic doesn't necessarily mean fatal -- the plant could just cause problems in their digestive system, or cause them pain or some other distress. A quick search before you buy means that you won't buy plants for your home or yard only to find out later that they may be harmful to your pets.
Toxic and Non-Toxic Plants [ASPCA]