Natural Lowcountry: Mistletoe brings kisses, trouble for trees

It may seem quaint and old-fashioned, but kissing under the mistletoe is still a Christmas tradition, particularly in England and the U.S.

Mistletoe has a rich cultural history dating back to Druid legends and Greek and Norse mythology. The plant was associated with peace, good fortune, protection from evil spirits, and of course, romance.

In Victorian England, each time a woman was kissed under a hanging sprig of mistletoe, a berry was picked from the cluster. When all the berries were gone, no more kissing was allowed.

Botanically, mistletoes comprise a heterogeneous collection of flowering plants in four different families. All are parasites on other plants.

We've even got mistletoe growing right here in the Lowcountry.

You may not have noticed it during the summer. But once trees start losing their leaves in the fall, it's easy to spot isolated clumps of vegetation flourishing high among the branches.

Those bushy, evergreen growths are native American mistletoe (Phoradendron serotinum), a distant relative of the English version (Viscum album).

American mistletoe infects over a hundred different host species, including elms, oaks, maples, and sycamores.

Technically, mistletoe is only partly parasitic, since it makes some of its own food through photosynthesis. But it also produces specialized tissues that invade the host's branches, soaking up water and vital nutrients.

American mistletoe may grow in a tree for many years without apparent damage to its host. However, some heavily infested trees can experience slower growth and poorer health. Bacteria, fungi, and insect pests may also invade the tree via mistletoe infection points.

In the fall, mistletoe produces small, inconspicuous flowers, followed by fleshy, white fruits. These are toxic to humans and pets.

But songbirds love to eat mistletoe berries, and they help disperse the seeds, which readily stick to tree bark wherever they're deposited.

The leaves are food for caterpillars of the great blue hairstreak butterfly (Atildes haleus), which is totally dependent upon American mistletoe for its survival.

Vicky McMillan, a retired biologist formerly at Colgate University, lives on Hilton Head Island.

This story was originally published December 13, 2015 at 6:04 AM with the headline "Natural Lowcountry: Mistletoe brings kisses, trouble for trees."