Journal articleThe genus Wall. ex Benth. is revised. Thirty-one species are recognised with three new species described: Bongch. from north-eastern Thailand, southern Laos and central Vietnam, Bongch. and Bongch. from northern Myanmar. Thirty names are lectotypified. A key to species, distribution maps and conservation categories for all species are provided.
Gomphostemma phetchaburiense (Lamiaceae), a new species from a limestone karst in southwest Thailand., a new species from Phetchaburi Province, Thailand, is described and illustrated. A key to the species of in Thailand is provided and conservation status and the dimorphic leaf characters are discussed.