FROSTWEED

frostweed, frost-weed, frostwort, Helianthemum canadense, Crocanthemum canadense

(noun) perennial of the eastern United States having early solitary yellow flowers followed by late petalless flowers; so-called because ice crystals form on it during first frosts

Source: WordNet® 3.1

Frost"weed`, n. (Bot.)

Definition: An American species of rockrose (Helianthemum Canadense), sometimes used in medicine as an astringent or aromatic tonic.

Note: It has large yellow flowers which are often sterile, and later it has abundant but inconspicuous flowers which bear seed. It is so called because, late in autumn, crystals of ice shoot from the cracked bark at the root; -- called also frostwort.

Source: Webster’s Unabridged Dictionary 1913 Edition