frostweed

from The Century Dictionary.

• noun A common name in the United States for the Helianthemum Canadense, or rock-rose: so called from the crystals of ice which shoot from the bursting bark toward the base of the stem during freezing weather in autumn. It has been used in medicine as a bitter and an astringent. Also called frostwort.

from the GNU version of the Collaborative International Dictionary of English.

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

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun botany An American species of rock rose, Helianthemum canadense, with large yellow flowers.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• 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
• noun tall perennial herb having clusters of white flowers; the eastern United States
• 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
• noun tall perennial herb having clusters of white flowers; the eastern United States