The oil of poison ivy (Urushiol) can stay on the fur of a dog and on shoes for weeks and a child could get a rash from petting the dog--or even touching shoes that have rubbed against the ivy a week or more later than the first contact with the ivy. One authority stated that the oil can remain on tools and/or clothing for up to a year.
For firefighters, telephone & electrical utility workers, and vegetative management persons, rash from these can be the greatest causes of Workers' Compensation claims.
An alkaline soap helps to dissolve the resins. Fat-based soap spreads the resin further. There are remedies one can purchase. Have one on hand just in case.
There have been at least 55 species of birds know to eat the fruit of poison ivy, dropping the seeds far and wide in their droppings.
There are many flowers with various poisons. Some will produce a rash on some with fair skin, some cause stomach problems, and some may lead to death.
POISON: The following are some of the more beautiful and sinister of such plants: angel trumpet, Azalea, Belladona (deadly nightshade), boxwood, buttercup, calla lily, caladium, clematis, daffodil, daphne, delphinium, Elephant ear, foxglove (digitalis), Hydrangea, Iris, larkspur, lily of the valley, mistletoe, opium poppy, periwinkle, philodendron, poke weed root, rhododendrum, berries from a trivit hedge, wisteria, sweet pea, lantana, lily, morning glory, and windflower.
It would be good to include the Australian stinging nettles (Dendrocnide moroides) to this list. The stinging nettle has many hollow stinging hairs on its leaves and stems. These act like syringes and inject histamine and other chemicals into whomever or whatever animal brushes against it. These cause a terrible painful sensation that can last up to three days or longer. The hollow hairs have a type of tiny bulb on top that falls away when rubbed against by humans or animals exposing the sharp tip.
Stinging nettles have, for centuries, been used for a variety of medicines as a diarrhetic, and to treat joint pain and other health concerns.
And we can never neglect Poison Ivy, an evil female character in Batman comics and movies.