ABSTRACT
The “asterids” (Figure 5.1) comprise 10 orders (APG, 2003), which resolve as a clade that is well supported by both molecular and nonmolecular characters (Soltis et al., 2005). This group corresponds much to the old Sympetalae (Monopetalae), a taxon uniting many families that were characterized by species with fused petals. Molecular data have been very helpful in refining the delimitation of the group, which is now circumscribed to include various families placed formerly in several disparate groups (Dilleniidae, Hamamelidae, Rosidae). Nearly a third of all angiosperm species occurs within the asterids, which include some 80, 000 species in 114 families (Soltis et al., 2005). Asterid species commonly produce iridoids, tropane alkaloids, and caffeic acid and possess flowers with an equal number of petals and stamens and unitegmic ovules with cellular endosperm (Judd et al., 2002; Soltis et al., 2005).
