Know Your Natives: Frostweed

Cleveland Powell

It may not look like much most of the year. But come winter, you’ll be amazed by this unpretentious perennial’s bone-chilling beauty.

For most of the year, frostweed is rather unassuming, blending in with other plants under live oaks and cedars. In midsummer it bolts, in moist locations reaching heights of six feet or more. Then as fall begins, frostweed (Verbesina virginica) blooms start to open.

frostweed

But the peak of frostweed’s bloom happens in October, just in time for the annual monarch migration.

It’s not just the timing of frostweed’s bloom that make it an important flower to sustain migrating monarch butterflies. Plants in the aster family have more nectar in a smaller area. That’s because their flowers consist of a cluster of two kinds of smaller flowers. At the base of each petal is a ray flower and at the center disk flowers, each with their own nectary. Add that to the physical structure — they’re flat and easy to land on — and frostweed becomes an extremely attractive flower to large butterflies like monarchs.

That’s not the only reason this hardy wild plant is starting to gain traction in cultivated landscapes around San Antonio. At summer’s end the massive leaves and winged stems crowned with white flowers set it apart from its neighbors. And later in the year if we get a frost, the sap in the stems freezes, creating beautiful ribbons of ice and giving frostweed its common name.

frostweed ribbons

A similar plant, Texas crownbeard, deserves a special mention here. It resembles a miniature frostweed, seldom making it to four feet tall and with even more ray and disk flowers, making it much showier. Bexar County is at the extreme northern end of its range, but wild populations can be seen at Mitchell Lake Audubon Center and the Medina River Natural Area. They can only be reliably told apart when they’re flowering, so now until November is a great time to catch a glimpse of this locally rare native plant.

If you’re interested in sustaining the monarch migration or just looking for a nice shade-loving backdrop plant, frostweed definitely deserves some consideration.

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