Friday, January 13, 2012

Urushiol - Sap of the Poison Ivy

I’ve told people to roll in Poison Ivy. To be fair, I’ve only asked people who insist they can roll in it but never develop a rash from it. So far no one has taken me up on my challenge.
Flowing through the vascular tissue of Poison Ivy (Toxicodendron radicans) and its relatives are liquid resins called urushiols that are contained in the sap. If exposed to skin, these oils can cause rashes varying in severity depending on the person. Generally speaking, only primate species are allergic. That includes us humans. I’ve never seen a monkey with a poison ivy rash nor have I seen one rolling in it. So far no monkey has taken me up on my challenge.
Deer browse on it. Turkeys, grouse and other ground grazers feed on the fruit to no ill effect. In fact, the seeds come out the other end with sufficient natural fertilizer, a bonus for the ivy.
Top left: Poison Ivy covering a hickory in Ipswich, MA
Top right: Poison Ivy reaches for the sky through the top of a Cabbage Palm
Bottom left: The glossy, dark green, lobed variety in ht Everglades

Bottom right: Jungle Pete collapses in the Poison Ivy after a 6 hour hike in the swamp

Identifying Poison Ivy is so tough for some, they wouldn’t know it if they had rolled in it. It can grow as ground cover, a small shrub or a climbing vine. In the swamps of the Everglades I’ve seenPoison Ivy winding 60 feet up the trunk of a cypress. Leaves can be dull to glossy, light to dark green and rounded to lobed based on location and time of year. Each leaf has three leaflets, but occasionally they do fall off and in the winter the leaves will turn color and fall off completely, even in Florida. Urushiol still flows through the plant at this time so beware.
There are some people that insist they are allergic if they just look at Poison Ivy. Were they looking at the plant as they held it? Some say they have never gotten it and others say they have developed or lost immunity to the oils. All of these are possible. But if you’ve developed immunity don’t tempt fate. Or do. Go roll in it. I think you’d be a complete sap.

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