PAULOWNIACEAE (empress tree family)

One genus, about 7 species, Asia.

The genus Paulownia has long vexed botanists, with some treating it as a peripheral taxon in the Scrophulariaceae (Steyermark, 1963; Armstrong, 1985) and others as an aberrant member of the Bignoniaceae (Cronquist, 1981, 1991). The presence of endosperm in the seeds, details of floral anatomy, and embryo structure are characteristic of the Scrophulariaceae, but the arborescent habit, leaf morphology, winged seeds, and chromosome number are more suggestive of the Bignoniaceae. Recent molecular research (Olmstead and Reeves, 1995) has not fully resolved the issue of familial classification, but has provided some support for treatment of the genus in its own family, a placement that has been accepted with some reluctance in the present work. Paulownia is most easily distinguished from the superficially similar Catalpa by its bluish purple corollas and ovoid fruits.