Labiatae, the fifth largest natural order of Dicotyledons (q.v.), including nearly 3,000 species under about 140 genera. They are mostly natives of warm or temperate regions, are all herbs or undershrubs, and have in almost all cases aromatic carminative volatile oils. They have stems which are generally square; opposite, decussate, exstipulate leaves; flowers in verticillasters (q.v.); a persistent gamosepalous calyx of five sepals, a bi-labiate gamopetalons corolla of five petals; didynamous stamens; and two carpels, splitting into four one-seeded superior nutlets, with a gynobasic style. Mint, sage, lavender, rosemary, and thyme are familiar representatives of the order.