2 (3)m, Gum Rockrose or Crimson Spot Rock Rose makes a tall, evergreen, woody shrub with glossy, sticky green, oblong lanceolate leaves, which have a strong, very pleasant balsam smell and are used to gain essential oils and a resign ("Labdanum") for incense. Makes beautiful, very large, pure white flowers with a crimson spot on each petal. Native of the Mediterranean. For any rich, well drained soil in full sun throughout the year. In colder climates best grown in an unheated wintergarden or greenhouse. USDA Climate Zone 9. IV-V.