White Crownbeard (Verbesina virginica)

September 4, 2011. We saw a ‘new’ white wildflower as we drove from McDuffie County into Wilkes County. At first there were only small plants with buds but then we encountered a large stand by the roadside. This is Verbesina virginica - known by the common names White Crownbeard, Common Frostweed, Tickweed, Iceplant, Iceweed, Virginia Crownbeard, Indian Tobacco, Richweed, Squawweed. During our trip, we saw it only in the Clarks Hill WMA in Wilkes Country, Georgia.

Part of the stand of plants

The leaves

Developing flower buds

A flower head

Close up of the flowers

Verbesina virginica has two subspecies, virginica and laciniata. The subspecies virginica is distributed more widely – from Pennsylvania west to Iowa and south to Texas - than laciniata which is only found in North and South Carolina, Georgia and Florida. In Georgia, this species is found mainly in the Piedmont and southwest counties as well as a couple of coastal counties. I don’t know which subspecies this plant is.

An interesting note: Verbesina virginica is known as frostweed because after it is exposed to freezing temperatures and still air, liquid water inside the stem freezes and splits the stem open, which then causes water and water vapor inside the stem to emit directly into the air. The water molecules then freeze upon exposure and form delicate ribbons of ice coming from the stem – see a photograph here. - USA Nature Phenology Network
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Distribution:
- United States Department of Agriculture Plants Database: Verbesina virginica (White Crownbeard)
- University of North Carolina Herbarium: Verbesina virginica

Identification resources:
- Southeastern Flora: White Crownbeard (Verbesina virginica)
- Natural and Naturalized Plants of the Carolinas and Georgia: Verbesina virginica (Common Frostweed, Tickweed)
- Missouri Plants: Verbesina virginica
- University of Texas at Austin, Native Plant Database: Verbesina virginica (Frostweed, White Crownbeard, Iceplant, Iceweed, Virginia Crownbeard, Indian Tobacco, Richweed, Squawweed)

Related posts:
- 2010: Year Of The Wildflower – Wildflower Index