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Frost Flowers
Ice ribbons, sometimes known as “ice flowers” or “frost flowers,” occur when the water in the soil remains above freezing while the air temperature falls below freezing. Warmer water in the soil is drawn up through the plant stems, either as part of the plant’s natural transportation system or through capillary action. As it travels up the stem, this water cools, freezes and expands, breaking the stem walls and creating a flow of ice. As crack after crack yields a layer of ice, the total effect resembles the many layers of a flower petal. Air bubbles trapped in the ice makes it appear frothy white.
If the air is cold and still when a frost flower forms, ice layers push straight out into large silvery feathers. When conditions cause the leading edge of ice to thaw slightly as it forms, the frost flower will curl inward around the stem like cotton candy on a stick. Each layer of ice is so thin the total frost flower is almost weightless and will shatter if touched.
Frost flowers occur in many parts of the world and in many areas of Arkansas. However, only a few species of plants are known to produce them. The formations never occur in exactly the same manner from one year to the next or even from one night to the next. Native Arkansas wildflowers that mature late in the year, such as yellow ironweed (
Verbesina alternifolia) and white crownbeard (
Verbesina virginica), are good frost flower prospects. In fact, white crownbeard is commonly called “frostweed.” Another native plant called dittany, stone mint or false oregano (
Cunila origanoides), is also known to produce ice flowers. Stems of these plants are still green and tender in late October and have a pithy core that can hold a lot of moisture–key factors in frost flower formation. Plants that are already dead, dry and brittle before the first hard freeze will not produce frost flowers.
Frost flowers have a brief life span. The first rays of the sun soften their delicate edges, and they melt quickly, so early morning is the best time to find them. Fencerows, stream banks, roadside ditches, city weed lots, weedy gardens and moist, open woodlands all are potential frost flower sites. They often form again on the same plants with successive hard freezes until all of the moisture is driven from the stems.
One responsibility of the Education and Information section of ANHC is to share our rich variety of data, information and resources with the public. When the public reaches out to us with questions (send yours to
arkansas@naturalheritage.org), researching the answer sometimes leads us to interesting connections.
On January 4, an email from Hot Springs Village asked if we could explain how “ice ribbons” are formed. In researching information about these unique ice formations, I saw references to several articles written by our conservation friend Dr. Bruce Means–discoverer of the Mean's giant earthworm–who we found last year while researching Arkansas endemic species. Dr. Means, president and executive director of the Coastal Plains Institute and Land Conservancy in Florida, is researching the possible adaptive significance of ice flowers and has published six articles about them over the last 20 years.
WANT TO SEE MORE FROST FLOWER PHOTOS? Visit Dr. Mean's gallery
here.
Update Date:
January, 14 2010