Around the Garden -- Poison Ivy, part two

"Poison ivy tree"

Some time ago, the Treefanatic posted a little information on poison ivy here. It is now full summer, and poison ivy has grown glossy and lush in those places where no one has thought to eradicate it. Often, poison ivy creeps in when one is not looking, and sets up housekeeping without so much as a by-your-leave.

Detail of poison ivy tree

In the photo at right, it has vanquished either an abandoned utility pole or a dead tree trunk – it would take a braver person than I to find out for sure. The location is a no man’s land between the Middletown Area Transit bus-loading area, City Hall, and Melilli Plaza.

To the left of the “poison ivy tree” is some shrubbery that is being strangled by bittersweet vines. When this picture was taken, a tendril of poison ivy and one of bittersweet were meeting in the gap and preparing to fight to the death. If the duel is allowed to continue, it will be interesting to see which is the victor.

Vines occupy a unique evolutionary niche, since they are adapted to accomplish the one thing other woody plants cannot: they travel, and at an amazing rate. By travel, I don’t mean they merely grow all over the place, although that is certainly the case. What is remarkable about their growth habit is that they put out roots wherever they go.

A distinctive characteristic of mature poison ivy is the mass of root hairs covering the woody stem – and these root hairs help to anchor the vine even on something as solid as tree bark. In addition to sinking down roots from above-ground stems, poison ivy can send up new plants from its below-ground, rhizome-like roots. When no trees or poles offer support, poison ivy adapts by becoming shrub-like, or romping across the garden like a ground-cover.

Most vines provide gazillions of seeds through their prolific berry production. Even poison ivy is a delicacy to some animals, primarily birds, but sometimes raccoons as well. This allows the plants to pop up anywhere and everywhere – usually directly under a bird’s favorite perch. This is a fine example of the plant’s adaptation: birds eat the berries, excrete the indigestible seeds around the base of a tree, the seeds germinate into a new vine which climbs yet another tree. Poison ivy spreads by conquering new territories – and, since birds often perch in trees at the edge of the woods, the poison ivy is assured of growing in sufficient sunlight.

Poison ivy will grow in almost any type of soil, but it does need a fair amount of sunlight. Usually you won’t find it growing in a very densely shaded area – fortunately. In my garden, it often grows next to a native wildflower called jewelweed, which some people find makes a great salve for poison ivy’s rash. I have not tried it, but some studies have shown its value. Jewelweed is related to the annual impatiens and has a sticky sap released when its stem is broken.

Still, the best precaution is to avoid all contact with poison ivy unless you are well protected with long sleeves, gloves and long pants. And, since animal fur can pick up poison ivy’s oil, it’s wise to keep pets far from it as well.