Verbesina virginica — Frostweed — Stem Rupture Detail
December 16, 2007 &mdash 24° F — N. Hays County, Texas

The ice formations seem to radiate from a multitude of points at right angles to the central vascular xylem, perhaps guided away from the center by the tissue that was pushed aside when the stem ruptured. Note that condensation frost has also formed on the epidermis and strands of tissue.