Leaves of Three, Let it Be

by Dr. Sarah Treanor Bois, PhD Director of Research & Education at the Linda Loring Nature Foundation

There is a children’s book of poetry called Love Poems for the Unloved by Diane Lang which highlights species in nature that are often given a bad rap. Some of the poems focus on spiders or snakes, others bats and vultures. In the spirit of appreciating something in nature that is often much maligned and which, quite honestly, I personally suffer from, let’s focus today on poison ivy.

Poison ivy (Toxicodendron radicans) is a woody plant native to Nantucket. Sometimes it looks like a forb, sometimes a vine it can take many forms. It is a in the same family of plants (Anacardiaceae) as mango and cashew. People who are extremely allergic to poison ivy may also be sensitive to those foods. As the name implies, it is “toxic” or “poisonous” to the touch for many individuals. While 85 % of Americans are allergic to poison ivy, they’re actually allergic to urushiol, the rash-causing oil produced by the plant.

Poison ivy is a plant I love to hate or hate to love. I am extremely allergic to the oil myself, but I marvel at its ability to morph into many plant forms. As a woody vine it climbs and girdles trees as can be seen along the edge of the Nantucket State Forest. It can appear herbaceous, growing among the low bush blueberries and wildflowers of summer (take care when you harvest). Each stem seems to know how tall to grow to mimic the surrounding plants. It can be shrubby in nature, growing in and among the bayberries and huckleberries growing no more than hip height. Despite being a master of disguise, there are some tell-tale identification clues so that you can avoid contact.

The first step in avoiding a rash is to know how to identify poison ivy. I always make sure to highlight the plant on nature explorations especially with kids. “Leaves of three, let it be,” is an old rhyme that works most of the time. While many native, innocuous plants also have clusters of three leaves, it may be best continued on page 22