There are 12 confirmed species of Paulowniaceae with potentially more as
hybrid,
variety, or mismatched
synonym species. However of these four genera currently only
Paulownia is a recognized member of Paulowniaceae. •
Paulownia •
Brandisia is settled in the Orobanchaceae as sister to the
Pterygiella due to molecular data from 9 chloroplast markers and samples from 6 of the 11
Brandisia species. They are a mostly shrublike family with hemi-parasitic characters that sometimes grow like climbing vines. Morphological similarities between
Bradisia and
Pterygiella, such as eglandular hairs on their capsules, reticulate seeds, and similar shaped tricolpate pollen, confirm their close relationship. There are still morphological characters as well as nuclear genome data to support
Wightia as sister to
Paulownia leading it to be of proposed hybrid origin from Phrymaceae and Paulowniaceae. This theory, based on chloroplast genome evidence, would explain its morphological similarities to both families. However the conflicts between the chloroplast, mitochondrial, and nuclear phylogenetic data make it unclear. If these were tested further and proven to be correct it should place
Wightia as a new family Wightiaceae. Since then there has been no more evidence or discussion on its placement, nor any available molecular data on a species under the name
Shiuyinghua silvestrii or
Paulownia silvestrii. ==References==