No frost, but frostweed did its icy trick

Early this week we had afternoon highs in the low 80s, but then an Arctic front came through and the weather turned bleak, windy, and cold. When I looked at the outside thermometer yesterday morning and saw that the temperature was 28°, I knew I had to drive the half-mile downhill to check the place in Great Hills Park where frostweed grows in goodly numbers. Sure enough, several dozen Verbesina virginica plants had done their magic ice trick, and I found plenty to photograph in the two hours that I spent out there in the cold (oh, the sacrifices that we nature photographers make).

Those of you in northern latitudes have lots of chances to take pictures of snow and ice, things that are rare down here in Austin. Today’s photograph shows the one form of ice that we have here that most of you have never seen, except perhaps in this blog for the past two years. If you’re not familiar with what’s going on here, I’ll repeat the explanation I’ve given before. The common name for this species comes from one of the strangest phenomena in botany. By the time of the first good overnight frost (i.e. freeze), almost all of these plants have gone to seed. Although each stalk stands there dried out and unappealing, the freeze can cause it to draw underground water up into its base. Now for the strange trick: the lower part of the stalk splits open as it extrudes freezing water laterally, and that process produces thin sheets of ice that curl out around the broken stalk.

In this latest photograph you’re looking at a pair of frostweed stalks, each with ice sheets scrolling in two directions.

© 2013 Steven Schwartzman