As part of our ongoing molecular systematic research into the phylogeny of the Lamiales, we have conducted an investigation of the hypothesis put forward by Cantino that the Australian endemic labiate tribe Westringieae (= Prostanthereae) and the Australian endemic verbenaceous tribe Chloantheae together form a monophyletic group, which also included Tectona (Verbenaceae/Viticoideae sensu Briquet). The evidence for this postulated relationship comes from a cladistic analysis of morphological and anatomical characters, in which members of these two groups come out adjacent to each other in an unrooted tree. A total of 58 sequences was analysed, including the 24 sequences representing Chloantheae and Westringieae, along with 33 sequences representing species from throughout the Lamiaceae (including Spartothamnella) and related families. The results provide strong support for monophyletic groups comprising Chloantheae, Westringieae, and those two clades combined (Prostantheroideae). Tectona is not found to belong to this group. Spartothamnella is found to not belong with the Prostantheroideae, but belongs in Teucrioideae. It is sister to another Australian endemic, Oncinocalyx, and together they are sister to the New Zealand endemic Teucridium. These three taxa, all formerly assigned to Verbenaceae, are most closely related to Teucrium, traditionally assigned to Lamiaceae.

Key words: Chloanthoideae, Lamiaceae, Prostanthereae, Verbenaceae