Paulownia was originally in the Family Scrophulariaceae but has been moved to its own family,
    although it can still be seen under Scrophulariaceae.
In China (the origin of many species) it is still in Scrophulariaceae.
In the the Mt. Coot-tha gardens in Brisbane it is under Scrophulariaceae.
Australian “Flora” uses Paulowniaceae as does Mabberley in his Plant Book with Scrophulariaceae s.l. as a synonym.

Paulownia has also been in Bignoniaceae which includes the very similar Catalpa trees.
Bignonia tomentosa is a synonym of Paulownia tomentosa and one Paulownia species is named Paulownia catalpifolia.

Depending on where it is placed there are 7 to 10 species.
Many species are cultivated for their light weight wood and there are a number of cultivars.