DISSERTATION RESEARCH: Systematics, Evolution, and Biogeography of Lepechinia (Lamiaceae)

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Systematics, evolution, and biogeography of Lepechinia (Lamiaceae)AbstractThe mint family (Lamiaceae) is a group of flowering plants that is well known for providing herbs used in cooking and ornamentals used in gardening. Many wild species also colour the landscape of the U.S. In California, a group of mint species in the genus Lepechinia occur in the area known as the California Floristic Province, a region extending from Southern Oregon to Northern Baja. This project will use DNA sequences of Lepechinia and fossils to determine when the California Floristic Province originated. Additional DNA sequences will be used to determine how closely related Lepechinia is to other groups of mints. Finally, the DNA data will be used to assess how the morphology and breeding system of Lepechinia have changed during evolution. The California Floristic Province has many plant species that occur nowhere else in the world. Because of its high diversity and unique set of species, there has been considerable interest in understanding how long it has been in existence and how it formed. Lepechinia and its close relative Salvia (a familiar garden plant) can help to determine the age of the flora. Preliminary results of this study show that the California clades of Lepechinia and Salvia originated between 10 and 20 million years ago, probably from ancestors that lived farther to the south.