Rock·rose n. Bot. A name given to any species of the genus Helianthemum, low shrubs or herbs with yellow flowers, especially the European Helianthemum vulgare and the American frostweed, Helianthemum Canadense.
 Cretan rockrose, a related shrub (Cistus Creticus), one of the plants yielding the fragrant gum called ladanum.

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 Frost·weed n. Bot. 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.

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 Helianthemum canadense
      n : 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 [syn: frostweed, frost-weed, frostwort, {Crocanthemum
          canadensei]