In Awe of Poison Ivy

We are never pleased to encounter poison ivy. We do see it every day on our regular hikes and we exterminate plants when they show up in our yards in Florida, both in the verdant central peninsula and in a dune-like site on the Gulf Coast. How does it do that? How can a plant be so successful and so persistent in so many varied habitats?

It seems to follow us everywhere. We were warned to stay away from it while growing up in the Adirondacks of northern New York State, Russ had painful brushes with it doing field work in Pennsylvania and Kansas, we tried to avoid having its leaves brush our eyes as we canoed through a forested swamp in South Carolina, and we marveled at six-inch diameter vines climbing aged tuliptrees while we worked on a box turtle study in a floodplain forest in Maryland. The USDA plants database shows its range extending from Hudson Bay on the north to south Florida, and we have heard it also extends into Mexico. A 1924 paper we came across cites its range limits as 15 to 50 degrees north latitude and 62 to 125 degrees west latitude. In more familiar terms that would include the area from Guatemala almost to Hudson Bay, and from Nova Scotia to the West Coast of North America. We are certain we will see it as we paddle the lower Suwannee.

What a plant and what adaptations! True, it is adaptable in growth form, occurring as a shrub, a ground-hugging vine, and a climbing vine like those towering ones we saw in Maryland. We suspect its toxin has much to do with its success, however. Humans are said to be uniquely susceptible to its poison, but it is likely that most animals are deterred from eating the leaves. We do know that birds find the berry-like fruits delectable and suffer no apparent harm from them. They carry the seeds far and wide.

Photographed 10/11/2010 near our home in north central Florida

On the edge of a Gulf Coast salt marsh, near Cedar Key 10-17-2010

Poison ivy is not our friend and we will never be happy to come across it in the field, but we will see it for what it is and give it grudging admiration as a uniquely successful plant.