Tuesday, December 23, 2008

My World: Frost Flowers

It's been cold in My World over the past few days.  We've experienced our lowest temperatures thus far this winter.  One of the most beautiful and delicate phenomena resulting from this cold are frost flowers, which are actually neither frost nor flower.

Frost flowers occur when the air temperature is below freezing but the ground remains unfrozen.  Here in the Ozarks, that is a fairly common wintertime event.  Our ground never freezes deeply and usually thaws between cold snaps. A frost flower forms when water inside a plant stem freezes, expands and is extruded through cracks in the stem forming thin ribbons of ice. Air bubbles trapped in the ice make it appear frothy white. The extruded ribbons of ice are often much more petal-like than the ones pictured above.

Not all plants form frost flowers.  Two of the more common ones that do are yellow ironweed (Verbesina alternifolia) and white crownbeard (Verbesina virginica). In fact, white crownbeard also is commonly called frostweed.

Wikipedia:  Frost Flowers
Missouri Conservationist Online

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