Monday, December 17, 2012

Hairy Vines

This is the time of year when the beautiful red leaves of the poison ivy and Virginia creeper have fallen off, leaving the hairy vines alone as they climb the trees.  Ordinarily I depend on the clusters of three leaves to identify poison ivy.  Virginia creeper generally has five leaves which serve as hosts to several sphinx moths and small blue fruits for songbirds to enjoy so we don't want to disturb them.

Poison ivy berries are also a healthy source of bird nutrition.  At least one source recommends that when controlling or eliminating it that you leave a few for the birds.  While a very wildlife friendly suggestion, remember that birds that eat the seeds also serve to deliver them all around.  On our land poison ivy isn't threatened with extinction unless Barb finds it.

Virginia Creeper- Jim Mason*
Poison Ivy- Jim Mason*






















Now that firewood cutting is in season, differentiating the vines becomes crucial.  Many of the dead or fallen trees are festooned with grape vines or Virginia creeper with poison ivy intertwined, trying to look innocent.  Large poison ivy vines may not even have visible leaves at ground level, while sprouting large clusters of tree like leaves high up.  Separating the ivy from the creeper is critical to maintaining a healthy, itch-free complexion.

The "hairs" of the two vines may look similar but they are quite different.  Poison ivy (Toxicodendron radicans) has thin aerial roots which attach to the tree by penetrating the dead outer layer of bark.  These are adventitious roots which in some other species are capable of extracting water and nutrition without being in the soil.  Poison ivy aerial roots simply cling harmlessly to the tree and do not function as extractors.  Although they seem to invite touching, don't, as they contain urushiol, the same toxic oil as the leaves and sap, all of which cause the same itching and blistering reaction.

The "hairs" on Virginia Creeper are actually tendrils.  The story of tendrils is the subject of another future blog.  They are modified leaves, petioles or stems adapted to climbing by wrapping around upright host plants.  Hiltonpond.org provides these details.
"Like the wild grapes to which it is related, Virginia Creeper produces stem tendrils, but their branched tips form into flat disks that produce a sticky substance. Once the mucilage dries and anchors the disk, the tendril coils contract and pulls the vine closer to its support (below right). This grasping mechanism is so powerful that Virginia Creeper can adhere to tree trunks, cliff faces, brick chimneys, and even plate glass windows. It's no wonder that Virginia Creeper often grows just as tall as the tree that supports it, and that it thrives in hardwood forests where trees are allowed to mature."
Now look again at the pictures above.  The fine hairy aerial roots of poison ivy are somewhat distinctive.  That said, it is best to avoid handling any hairy vine if you can't see the leaves, unless you are "itching" for trouble.

*Jim Mason, Naturalist at the Great Plains Nature Center in Wichita, Kansas.  More of his pictures and information are at gpnc.org

Another site with pictures of look-alikes is at www.purplebutterflies.com

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