Plant of the Month | October 29, 2013

Plant Of The Month: Frostweed

Frostweed seems to be a plant that people either hate or love. In semi-shady locations it can spread by rhizomes to form large colonies of coarse looking plants that can get up to 6’ tall.

Some consider this an ugly and invasive weed. However, in late summer it gets large, white flower heads 3” to 6” across that are an important nectar source for fall butterflies, including migrating Monarchs that are returning from the northern US to overwinter in Mexico.

Another interesting characteristic of this plant is a phenomenon that gives it its common name. The sap of the plant freezes near the base of the stem after the first hard freeze of the season, forming interesting shapes that have been variously described as ice ribbons, ice flowers, and ice leaves, among many others. This happens only once in a season, and in order to observe it, one must get out before temperatures rise to above freezing, when the frozen ice melts. A few other species of plants have also been reported to form these ice formations. More information on this phenomenon can be found at: http://w3.biosci.utexas.edu/prc/VEVI3/crystallofolia.html.

Frostweed can serve a useful purpose in the landscape, where it can be used as a transition plant between manicured flower beds and wild areas. Given that it is very drought tolerant and deer resistant, and serves as a beneficial wildlife plant, perhaps it should be loved more than it is.

Text by John Siemssen. Photos by Norman G. Flaigg and Melody Lytle, Wildflower Center