AUSTIN (KXAN) — The Valentine’s Day weekend winter storm brought very unusual weather into Central Texas. Two of the things that we likely won’t see again in our area for some time are hair ice and frostweed.
KXAN viewers sent in multiple photos of a strange ice formation on local plants. This plant is called frostweed and is native to Central Texas. Also known as Verbesina virginica, this plant is capable of producing strange ice sculptures under the right conditions.
The other type of icy formation is called hair ice, sometimes called ice wool or frost beard, and it is a delicate ice formation that grows on dead trees in the north. Both hair ice and the icy formations on frostweed require cold temperatures with a high humidity, something that’s uncommon in Central Texas.
Both formations grow in a similar way. Trees and stemmed plants are covered with tiny tubes filled with water that act sort of like veins. When the air is really humid and just below freezing, the water that’s at the end of these tubes freezes and expands, turning into ice.
This ice pushes itself outside the tree tube and into the air. When this happens, the ice pulls the water that’s in the tree’s veins with it. That water then freezes and pulls more water with it.
This cycle repeats itself until it looks like the dead tree is growing hair.
In 2015, researchers discovered hair ice’s roots come from a special fungus, Exidiopsis effusa. The researchers believe that this fungus, which has been found in all hair ice samples, acts like hair spray and gives the ice its shape.
Hair ice has a diameter of 0.02 millimeters, much smaller than actual hair. Because hair ice requires such specific conditions, we likely won’t see it in our area again for some time.