Lamiaceae
Introduction
The Lamiaceae, or mint family, is the seventh largest flowering plant family with about 7,000 species organised into 236 genera, including woody herbs, shrubs, trees and even woody climbers. Many are of horticultural or economic importance, including culinary herbs such as basil (Ocimum), fragrant oils such as lavender (Lavandula), and important timber trees such as teak (Tectona grandis). Lamiaceae are also widely used in traditional medicine. The Lamiaceae is therefore a significant component of global plant diversity, particularly in the drylands.
The multidisciplinary work of the Lamiaceae team includes displays of horticulturally important genera, writing accounts for much-needed tropical Floras, sequencing specific regions of the genome to investigate the affinities of groups within the family, and analysing members of the family for biologically active compounds. As in other systematic teams, the Lamiaceae team’s objective is to gain a deeper understanding of the family and its close relatives through high quality research in collaboration with a wider international network, thereby generating a greater understanding of the diversity, utility and conservation needs of this important plant group. The tropical tribe Ocimeae (basil and allies) has provided a focus for activities over the last ten years. This focus is now beginning to move towards subfamily Viticoideae (teak, Vitex and its allies) and the medicinally and horticulturally important genus Salvia.
The multidisciplinary research in Lamiaceae involves staff from the Herbaceous and Alpine and Technical Glass Sections of HPE, the Molecular Systematics, Micromorphology and Sustainable Uses of Plants Sections of the Jodrell Laboratory and Herbarium staff. This expertise is strengthened by a network of international collaborators. The best example of this integration is the team’s work on tribe Ocimeae (basil and allies) and in particular the economically and medicinally important genera Lavandula, Ocimum (basil) and Plectranthus. The extensive herbarium, living and DNA collections at Kew were used as the basis for the study. Baseline inventory work included major revisions of the group in Africa and SE Asia. A revision of Lavandula, which addressed the needs of taxonomic, conservation and horticultural audiences, was completed and a herbaceous border illustrating the diversity of Lavandula finalised. A revision of Plectranthus was used to demonstrate the value of Herbarium collections in production of preliminary conservation assessments in collaboration with the GIS unit and 81 species conservation assessments of Ocimeae have been disseminated. Comparative work resulted in a paper in a benchmark paper which presented a molecular phylogeny of the Ocimeae and used it to elucidate relationships, biogeography and the distribution of morphological, palynological and phytochemical characters. The phylogeny was then used as a framework for a review of the ethnobotanical uses of Plectranthus. This multidisciplinary work in Ocimeae also served as a basis for investigating the distribution of flavonoids and diterpenes in the tribe. This focused approach allowed integration of a number of collaborative relationships involving researchers in Kenya, Ghana, Malawi, South Africa, Thailand, Ireland, Denmark and the UK. It is envisaged that similar programmes of multidisciplinary work, focused on subfamily Viticoideae and Salvia will be conducted over the next review period.
The broad-based collections and expertise at Kew, coupled with a productive network of collaboration also enables large-scale studies of the Lamiaceae and also broader studies involving related families in the Lamiales. Baseline generic level treatments of Lamiaceae and Verbenaceae prepared for Kubitzki’s Families and Genera of Vascular Plants, and phytochemical and floral morphology studies in, for example, Acanthaceae, Gesneriaceae and Plantaginaceae, help place evolutionary studies of the Lamiaceae in a broader phylogenetic context.