Either of two perennials of the eastern United States on which ice crystals tend to form from exuded sap under freezing conditions: Crocanthemum canadense (family Cistaceae), which has yellow flowers and is used medicinally as a tonic and an astringent, and a crown beard, Verbesina virginica, which has small white flowers.
Origin
Early 19th century.
Definition of frostweed in US English:
frostweed
noun
Either of two perennials of the eastern United States on which ice crystals tend to form from exuded sap under freezing conditions: Crocanthemum canadense (family Cistaceae), which has yellow flowers and is used medicinally as a tonic and an astringent, and a crown beard, Verbesina virginica, which has small white flowers.