Summary This project aims at studying how plant secondary compounds protect plants against climate stress. We study the Mediterranean aromatic herbs that are famous for their many fragrances used as culinaric herbs and pharmaceuticals. These plants are exceptional because they produce large amount of monoterpenes in their essential oil, and because both within and a among species different plants differ in the identity of their dominant monoterpene. These different chemical types are associated with different tolerance to climate stress. Understanding how the different monoterpenes safeguard the plants against different types of climate stress (heat, drought, frost) are fundamental to understand how species respond to current, and potentially adapt to future climatic conditions.