Systematics of Lamiaceae subfamily Viticoideae and allies
The re-curation of the Lamiaceae by Harley and others in 2004 recognised seven subfamilies; the least satisfactory of these is subfamily Viticoideae. The c. 400 species in the Viticoideae occur predominantly in the tropics in both wet and seasonally dry habitats. The most species rich genus is Vitex, of some economic importance as a timber tree, and used medicinally (e.g. Vitex agnus-castus). Historically allied to the Viticoideae are Tectona, a genus of three species including Tectona grandis (teak), famous for its durable and attractive wood, and Callicarpa, a larger genus of c. 140 species, that includes species used in horticulture (e.g. Callicarpa bodinieri var. giraldii).
Molecular phylogenetic work has demonstrated that the subfamily Viticoideae is not a natural group (not monophyletic): the placement of economically important genera such as Tectona and Vitex within the Lamiaceae is yet to be resolved. The Viticoideae and allies are also poorly known taxonomically, and are hence a focus for the Lamiaceae team (see sister project South East Asian Floristics: Lamiaceae). An important first step has been to clarify the generic limits within the group.
An updated phylogeny of Vitex and allies was published in 2009 (Bramley, Forest & de Kok, 2009, Taxon 58: 500-510); several South East Asian genera were subsumed into Vitex (Paravitex, Tsoongia, Viticipremna). The relationship between Teijsmanniodendron and Vitex remains unclear. Further work based on an enlarged sample is required to confirm the position of Petitia and Pseudocarpidium, both New World genera allied to Vitex.
Through a combination of approaches (molecular phylogenetics; alpha taxonomy; chemosystematics) we hope to resolve the relationship between the unplaced genera Tectona and Callicarpa and the remainder of the Lamiaceae; both Tectona and Callicarpa have historically considered as closely related to the Viticoideae. This work is likely to become part of a global collaboration that aims to produce a resolved phylogeny of the Lamiaceae.
The biological activity of Vitex species is being investigated by Kew’s sustainable uses group; a PhD study is investigating the ethnobotany of the Vitex trifolia species complex.
Project partners and collaborators
- Universiti Putra Malaysia
- Forest Research Institute Malaysia (FRIM)
- PortugalUniversity of Coimbra
- ThailandKhon Kaen University
- Royal Botanic Garden Edinburgh
- Birkbeck College