Heliotropiaceae are a cosmopolitan family of flowering plants with approximately 450 species worldwide, though it is concentrated especially in the tropics and subtropics. The following are the four genera in the family: Heliotropium (incl. Tournefortia L.) Euploca Nutt. Ixorhea Fenzl Myriopus Small Ixorhea is sister to Euploca and Myriopus. Together they form a clade sister to Heliotropium, which comprises four major clades: Heliotropium sect. Heliothamnus I.M.Johnst., Old World Heliotropium, Heliotropium sect. Cochranea (Miers) Post & Kuntze, and the Tournefortia-clade, the latter comprising Tournefortia sect. Tournefortia and all remaining New World species of Heliotropium. Source: Wikipedia (en)