I had someone ask me that question the other day – and either way, you don’t want them in the garden.
Both are plants that cause a red, itchy rash – sometimes blistering, as a result of contact with the oil contained within the plant – urushiol (yoo-roo-she-all). You will get the rash from contact with any part of the plant, flowers, berries, leaves, roots – even dead ones – so always wear long gloves and eye protection when erradicating poison ivy or oak. You can even get the rash from touching something that has come in contact with the plant – clothing, tools, even pet fur.
Both plants can be identified by their distinct 3-leaf arrangement. Poison ivy can grow as a shrub, reaching up to 4-feet high, as a groundcover, or climbing vine. The almond-shape leaves range from light to dark green and turn brilliant red in the fall. Poison ivy produces flowers, and then small berries that are a beigy-grey-white shade.
Poison oak has a scalloped 3-leaf arrangement that looks very similar to true oak leaves. Grown as a dense shrub or climing vine, the leaf shades vary from bronze to bright green to red, depending on the season.