|Credit: Marvin Smith|
Frost flowers are produced on only a few varieties of plants when the air temperature is below freezing and moisture in the plant stem is still liquid. Plants hold water in their stems, and water expands when frozen, so long thin cracks can form along the stem. Water is drawn through those cracks and freezes upon contact with the air. Water continues to flow out, forming layers that resemble petals. This has only been observed in a few species of plants: the white crownbeard (Verbesina virginica, a.k.a., frostweed), yellow ironweed (Verbesina alterifolia) and Helianthemum canadense. In woody plants and tree branches, the seeping water freezes into long strings of ice that look like strands of hair: "frost beard."
|Frost flower in the Ozark Mountains. |
Credit: Marvin Smith, via Wikimedia Commons.
|Frost beard taken at Mount Maxwell, Salt Spring Island, BC. |
Public domain, via Wikimedia Commons.