As the holiday season comes into the home stretch, red and green are everywhere to be seen. Retail establishments, homes, and just about everywhere else humans frequent are awash in the colors red and green.
While the leaves of many deciduous trees, weeds and shrubs have converted to a shade of brown, two common local native vines are displaying holiday colors.
Both Virginia Creeper (which is called Florida Creeper in Virginia) and poison ivy can be a bright cherry red during the waning days of autumn and early winter. With the seasonal change, it may be difficult to tell the two species apart.
Poison Ivy (Toxicodendron radicans) and Virginia Creeper (Parthenocissus quinquefolia) both grow in protected areas under the canopy of trees. Only poison ivy produces urushiol, a plant oil which will cause a severe skin rash when any part of the plant is touched.
Poison ivy utilizes the same structures as Virginia creeper and its seasonal color is similar, but it has a far different effect when physically contacted. As the old saying goes, “leaves of three, let it be!!!”
The reds and purples in the leaves currently on display come from a pigment group called anthocyanins which resides in the cells. This chemical compound develops in the sap of the leaves.
These pigments are not present in the leaf during much of the growing season, but they begin to be produced in August and September as the days become noticeably shorter. The amount and intensity of the reds and purples in leaves depends on a combination of environmental factors.
The breakdown of sugars in the sap, the intensity and duration of sunlight and the level at which phosphate declines in the leaf combine to produce a nearly infinite number of shade and hue possibilities.
The brightest colorations commonly occur when the fall days are bright and cool, and the nights are cold but not below freezing. Poison ivy and Virginia creeper often grow together and can be difficult to differentiate, but there is a critical trait which may help distinguish the two species.
In the case of poison ivy, allergic reaction occurs by touching the plant, or by coming into contact with the oil on animals, tools, clothes, shoes, or other items which have struck the plant. Even the smoke from burning the plants contains oil particles which can be inhaled, causing lung and airway irritation.
Contact dermatitis is not a problem with Virginia creeper. While difficult to control, there are some horticultural uses for this plant.
Virginia Creeper, with its five-leaf grouping, is making its seasonal color shift. Leaves under trees have been protected from the frost, but as the calendar moves into 2018 they will soon drop.
Poison ivy and Virginia creeper both grow in heavy shady or sunny locations throughout the Big Bend region and Florida. Each can produce a vine up to 150 feet tall that climbs high on trees, walls, and fences or trails along the ground.
Both plants are common along old, unmanaged fence rows and the edges of paths and roadways. Only poison ivy contains urushiol, the skin irritant. This compound is present at all times of the year, even when bare of leaves and fruit in winter.
The leaf shape and the form of the leaf are one telling factor. Poison ivy always has three leaflets, and Virginia creeper usually, but not always, has five leaves at the end of a stem.
It is important to remember blackberries have three leaves on a cluster, but they do not turn red in the autumn. Also, blackberries have thorns on their vines.
The other easy identifier is the berries produced. Poison ivy’s are white, and Virginia creeper’s are purple to black.
If contact is made with the wrong vine, hope Santa brings some anti-itch ointment. Maybe poison ivy is really the reason Rudolf’s nose is so red?
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