The Collaborative International Dictionary of English v.0.48:

Rockrose \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.
   [1913 Webster]

   Cretan rockrose, a related shrub (Cistus Creticus), one
      of the plants yielding the fragrant gum called ladanum.
      [1913 Webster]