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Fall 2010

Urban Jungle

The changing natural world at our doorsteps | Illustration and text by Patterson Clark      

Virginia Creeper

November 2, 2010

Virginia creeper
letting its fruit flag fly

As autumn nears its midpoint,
Virginia creeper leaves turn brilliant red,
a signal for nomadic birds to stop
for an in-flight meal

If "leaves of three, let it be" is good advice for poison ivy, then "leaves of five, let it thrive" should be the maxim for Virginia creeper.

The native vine plays a major role in feeding fruit-eating songbirds on their way south, especially thrushes, gray catbirds and common yellowthroats.

Leaves turn red just as the blue-gray fruits ripen. The plant may rely on this foliar fruit flag to alert migrating birds to a food opportunity. Timing is critical: The fruits are high in lipids (fats), which don't stay fresh for long.

While birds may wolf down the berries, people shouldn't follow suit, as the fruits are potentially toxic to humans.

The leaves aren't so people-friendly, either. When they are bruised, specialized cells rupture, releasing irritating microscopic needles of calcium oxalate, which can trigger contact dermatitis.

Scaling trees, rocks and houses, Virginia creeper secures itself with tendrils tipped with tiny pads that cement themselves to vertical surfaces.

A creeper-covered brick wall will stay cool in the summer, the masonry undamaged by the vine's tendrils. Wood siding, however, will rot in the humid environment harbored by the vine.

Sources: Edmund W. Stiles, "Patterns of fruit presentation and seed dispersal in bird-disseminated woody plants in the eastern deciduous forest," the American Naturalist; USDA; "Interactions between passerines and woody plants at a migratory stop-over site: Fruit consumption and the potential for seed dispersal," Claramarie Moss, University of Virginia