Wednesday, October 21, 2015

Wednesday's Wildflower: White Frostweed

The air is is alive with the hum of insects during these last warm weeks before winter tightens its icy grip.

Monarchs are fueling up for their long journey to Mexico, female bumble bees are getting their last meals before retiring underground until the following spring, and other pollinators are busy securing the next generation before their life cycles play out.

Late season flowers are crucial to these pollinators and many more, offering up their precious nectar in their time of greatest need.

One of these all important flowers is White Frostweed, and it can be seen blooming across much of the eastern United States.

It may not be the showiest autumn wildflower, but it is one of the most prominent.

White Frostweed can be seen towering in great drifts just about anywhere: stream banks, roadsides, forest edges, power line right-of-ways, fields, pastures, open woods and waste places.

It can grow 3-7 feet tall, with coarse, grayish foliage and alternating, broad lanceolate leaves growing from winged petioles.

The stems are covered in a soft, white down.

The blooms are composed of white disc flowers with purplish anthers, and five white rays.

The snow-white blooms begin to open in August, and can sometimes still be seen as late as November, depending on the region.

It goes by a few other common names like White Crownbeard, Virginia Crownbeard, Frost Flower, Ice Plant, Iceweed, Indian Tobacco, Richweed, Squawweed, and Tickweed.

The plant's association with frost isn't necessarily because of its late bloom time. The name stems from a phenomenon that occurs long after the blooms fade.

During the first hard freeze, usually sometime in late autumn or early winter, Frostweed forces water out of its stem.

It tends to happen on the really cold, still nights, often splitting the epidermis on its way out. This water vapor freezes as it escapes.

The result is a peculiar little ice formation at the plant's base, known as a "frost flower."

Verbesina virginica (Frostweed)
Wildflower Center
These delicate ice curls can be seen first thing in the morning, and often linger for awhile, especially if the temperatures stay below freezing.

Wildflower Center
It is thought that removing this excess moisture may help prevent damage to its tissues from ice crystals forming, but nobody knows for sure.

The crystals form higher on the plants' stems earlier in the season, and are larger because there is more moisture released. Later in winter, the frost flowers are smaller and form mostly at the plant's base.

Plant Resource Center
These ice crystals go by a long list of colorful nicknames: ice ribbons, ice flowers, ice fringes, ice fingers, ice filaments, ice leaves, frost ribbons, frost streaks, frost beards, frost castles, rabbit ice and rabbit butter.
Its Latin name is Verbesina virginica. Verbesina is thought to have originated from the genus name Verbena, with the ina part meaning resemblance, or to "resemble verbena."

There are a few other members of this genus that can be seen blooming in unison with their white cousin.

Yellow Crownbeard (V. occidentalis) is one of them.

It grows roughly the same height, and usually right alongside White Frostweed, making for a lovely mix of yellow and white along woodland edges and moist thickets.

Its flowers typically only have 1-3 rays, or sometimes none at all.

Another member of this genus which is also found in conjunction with Verbesina virginica is Verbesina alternifolia, or Wingstem.

It is showier than V. occidentalis, and grows taller, sometimes reaching as high as 10 feet.

It is easily recognized by its panicles of showy, reflexed rays and spheres of numerous disc flowers.

All three species can sometimes be found growing together, but White Frostweed and Wingstem prefer sunnier conditions.

There apparently haven't been very many medicinal uses for the genus Verbesina.

The only use I was able to find specifically for V. virginica comes from King's American Dispensatory 1898, where it was hailed as a diuretic, found to be especially useful for its solvent effect on "calculi in the bladder."

These properties have yet to be proven by modern testing.

While it may not have many practical uses for human beings (other than pleasing the eyes, of course), White Frostweed and its counterparts are a vital food source as the growing season draws to a close.

Every pollinator that is still active during the fall depends on plants like Frostweed for their nectar and pollen.

 Viceroy Butterfly
Pennsylvania Leatherwing Beetle
Tawny Emperor Butterfly
Native Bee
 Because its foliage is quite bitter, it is largely left alone by herbivores, except in overpopulated areas.

The leaves provide food for several species of moth and butterfly caterpillars, and the plants are sometimes hosts to gall-producing insects like certain species of fly and beetle larvae.

Here in middle Tennessee, the leaves are beginning to fall, and soon the landscape will surge into one last color explosion before the subdued palette of winter settles all around us. Let's savor every moment.

Be sure to join us for next Wednesday's wildflower!

Click here to read about last week's wildflower, Great Blue Lobelia.

Medicinal information herein is shared strictly for anecdotal purposes. Do not attempt to self-medicate with wild herbs. Please consult a doctor first.


Wildflower Center

Plant Resources Center

Henriette's Herbal Homepage

Wildflowers of Tennessee, the Ohio Valley and the Southern Appalachians - Dennis Horn & Tavia Cathcart


  1. Beautiful pictures! Thanks for linking up to Simply Natural Saturdays!

  2. Thanks for sharing at My Flagstaff Home!


  3. This has to be the coolest one yet! I have never seen anything like it. I do think I've seen these flowers around though, so I'll be looking for these frost flowers on my morning run when it starts to freeze!

    Thanks for linking up with Green Thumb Thursday. I hope to see you again this week!


  4. That's really cool. I've never seen anything like it.