The asterids are an extraordinarily diverse group of extant angiosperms that includes more than 80 000 species. The clade also includes two of the most species-rich angiosperm families, the Asteraceae and the Rubiaceae (Bremer et al., 2004) as well as some of the largest angiosperm genera (e.g. Solanum). Asterids have an extensive fossil record in the Cenozoic, but their representation in the Cretaceous is more limited and largely confined to Cornales and Ericales.

Classification of asterids

As currently defined by molecular data, asterids include four major clades: Cornales, Ericales, lamiids (Euasterid I), and campanulids (Euasterid II) (Figure 15.1). Cornales are resolved as the earliest-diverging of these four main lineages. They are followed by the Ericales, which are sister to the core asterids, which comprises lamiids and campanulids (APGIII, 2009). Molecular support for the recognition of the asterids as a whole is good, and there is also generally strong support for relationships within the group, although molecular support for the campanulids is weak (Judd and Olmstead, 2004; Soltis et al., 2005).