Heliotrope (Heliotropium arborescens) produces dense, flat clusters of deep purple, lavender, or white flowers with a vanilla fragrance and deeply crinkled dark green leaves. It's sometimes called cherry pie plant because of the cherry undertones to the vanilla scent. Heliotrope is a tender perennial that can be grown all year outdoors in Zones 9-11 (in Zones 8 and colder, grow it as an annual).