Marigolds are not listed as a poisonous plant for humans, according to the National Capital Poison Center. Marigolds are considered safe and were historically used as medicines for healing wounds and preventing infection in tinctures, ointments or infusions, according to Herbs 2000.
The American Society for the Prevention of Cruelty to Animals lists common garden marigolds, also known as Calendula officinalis, as being nontoxic to dogs and cats, as well. The ASPCA notes that some other common names for the Calendula officinalis flower include mary bud, gold bloom or pot marigold. Marigolds are part of the Compositae family of plants.