Frost Flowers

If ever you've walked in a wooded Ozark hillside, you have passed this week's subject a thousand times without noticing, without bending over to stroke this small plant's oregano-scented leaves. Likely to you it's just more undifferentiated understory greenery.

It's a small plant, one-to-two feet tall, with wiry uninteresting branched stalks and oval, inch-long leaves loosely scattered along the stem. It's blooming now, but again, you've probably missed that too, as the blue-purple flowers, although beautiful, are barely ¼ inch long. The plant has brushed your shins and calves, but you never even noticed. Chances are you simply stepped on it.

The little plant of which I speak is called American dittany, stonemint, or in the Ozarks, feverplant, as it was once brewed into a tea and sipped to help break a fever. As one nineteenth-century book put it, "used beneficially in slight fevers and colds, with a view to excite perspiration."

Introduced to English horticulture by 1777, this native of North America "has a strong scent, and an infusion of it is used in North America by persons who have taken cold, or have pains in the limbs," according to Swede Peter Kalm, whose Travels in North America (in 1750) was published in Swedish in 1753, then in English in 1770. Those of a botanical ilk, like me, call it Cunila origanoides, a member of the mint family. The name Cunila is of uncertain origin. The species name "origanoides" means "oregano-like" in reference to the fragrance.

Why bother with this little non-descript native plant now? It is the hour of its greatest glory! During the first chills of autumn frosts, dittany produces ephemera "frost flowers" at its base -- twisting, white, fluted ribbons of ice, sometimes four inches tall and two inches broad, like magic ribbon candy making a ghostly Halloween appearance.

The frost flower phenomenon is caused by cell sap rising from the still-alive root into the dead tissues of the leaves and stems. Rising vapors seep through cracks in the stem, crystallizing as they contact freezing air. To be appreciated, frost flowers must be seen.

Only a few plant species produce frost flowers. Another is Virginia Frostweed, (Verbesina virginica), with frost flowers hugging a three-foot tall stem, which you may have seen while driving to work on a frosty morning this time of year.

To see dittany's frost flowers, you must get into the woods before the first sunlight melts away another ephemeral surprise from Mother Nature.