"The formation of frost flowers, also known as "ice flowers," is dependent on a freezing weather condition occurring when the ground is not already frozen. The sap in the stem of the plants will expand (water expands when frozen), causing long, thin cracks to form along the length of the stem. Water is then drawn through these cracks via capillary action and freezes upon contact with the air. As more water is drawn through the cracks it pushes the thin ice layers further from the stem, causing a thin "petal" to form."
|Late summer flowers, Cunila origanoides|
I learned about this condition only recently by way of a friend in the Georgia Native Plant Society. She called it "crystallofolia" and provided some pictures of dittany (Cunila origanoides) in her yard exhibiting the condition. Another friend used those pictures to write an article about it for the January newsletter. Still - I didn't expect to see it myself. We've had some warm weather lately but earlier this week it got very cold - below 20 overnight!
After a tip from my friend Jane that she found some in her yard, I went outside to look. Bingo! My dittany had frost flowers too!
While this oozing, freezing, "flowering" event is very exciting, photographing it is so not easy! Here is a picture of the frost flowers in my yard:
A much better picture belongs to my friend Jane - she sent me this picture of the frost flowers on her Joe-Pye weed (Eupatorium sp.):
This subject is a popular topic this week due to the cold snap throughout the eastern U.S. Gail over at the blog Clay and Limestone also has a post on this with some very excellent pictures of Verbesina virginica from Tennessee.