Leaves of 3, let it be: Part 1

A plant everyone needs to know how to identify, whether they are nature lovers or not: Poison Ivy. Since birds eat the berries and deposit the seeds, the plant can pop up in unexpected places such as our yards and even in the city.

There is a saying, “Leaves of three, let it be!” Actually, the saying should be “Leaflets of three …” because one leaf has three smaller leaflets. This saying is a good starting point, but there are many other plants with three leaves. Poison Ivy usually has notched, pointed leaflets, the two lower leaflets have very short stems known as petioles, the middle leaflet has a longer petiole.

Often, the area where the three petioles are attached is reddish in color. In the spring, newly emerged leaves have a reddish hue due to the pigment called anthocyanin found in the cells. It is a form of sunscreen for the leaf before the green chlorophyll develops. In the fall, the red, yellow and orange pigments give the leaves their beautiful autumn colors.

Since the chemical urushiol found in Poison Ivy that causes the miserable rash is found in all parts of the plant, including the stem, it is important to know what the plant looks like without leaves. Poison Ivy is a perennial plant, so it does not die in the winter.

The young plants growing on the ground have a light brown stem. The leaf scars from the previous year are slightly heart shaped. Older vines growing on trees are very hairy with numerous holding roots that clasp the bark. The branches growing off the older vines can resemble tree branches; it is important to watch out for them while walking in the woods.

Poison Ivy has small green flowers that bloom in the summer. As fall approaches, off-white berries form on the vines, especially the ones growing in the trees. Even though the berries also contain urushiol oil, birds are able to eat them, spreading the seeds throughout the forest and urban areas.

Don’t let the fear of Poison Ivy keep you from enjoying the outdoors. Wear long pants when hiking where it may grow. If you come in contact, be sure to wash the area with soap and warm water within 20 minutes of exposure.

Part 2 will discuss other plants with “leaves of 3!”

Kris Light photographs wildflowers, animals and anything of interest with many of her best photos used in her website: click Search All Galleries to see photos. Her Outreach Science classes are available for public, private and homeschool groups through the AMSE. Kris welcomes questions at email.