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.