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An Early Spring Performance by Verbesina virginica, Feb. 13, 2008

by Bob Harms ()
On Feb. 13, at only 29° F, our V. virginica was yet again recorded with crystallofolia. As the result of previous ruptures all plants had already lost their epidermis down to the very base, perhaps 1 cm. from the ground. And only c. 5% of stems displayed ice crystals — and no Pluchea odorata. The amount of ice was minimal at best, and might not have been noticed had I not been looking for it.

The only apparent source of pressure was root pressure, no doubt drawing water as the result of evaporation at the surface of the exposed xylem rays. On many stems the rays had split, clearly the result of water freezing in the stem.

The two larger plants shown on other pages. The picture on the right was taken in the afternoon, showing the new shoots already in an advanced stage.

A selection of pictures from Feb. 13 (click to enlarge):


Same stem as that on the left.