I have known several people who used to brag that they don’t respond to poison ivy. Now they do- sometimes it just takes certain people more exposure to sensitize themselves to it.
Just a few common plants called “ivy”
Grape Ivy: Cissus rhombifolia. A houseplant in the US. In the grape family.
German Ivy, also called Cape Ivy: Delairea odorata, previously classified as Senecio mikanioides. In the Daisy family. Houseplant, noxious weed in warm areas such as California. From South Africa.
Boston Ivy: Parthenocissus quinquefolia. From China. Closely related to Virginia creeper, Parthenocissus tricuspidata, a North American native. Also in the grape family.
English Ivy, sometimes called true ivy: Hedera helix. Native to Europe. In the Aralia family.
Poison Ivy: Toxidendron radicans. Closely related to Poison Oak, Toxidendron diversilobum. In the Sumac family (like cashews!)
People call anything that climbs, with smallish, vaguely grape-like leaves “ivy”. This is why correct botanical binomial nomenclature is so useful.
I think you have those back to front. P quinquefolia is usually referred to as Virginia creeper, and is a North American native. P tricuspidata is the Asian one.
Virginia creeper has compound leaves composed of five “leaflets” radiating from a central point. Boston ivy has three-lobed simple leaves.
Yes, I mixed it up. Thank you!