A large tree, intermediate in appearance between its parents. Flowerhead broadly conical, to 80 cm tall; cymes with short but distinct peduncles 6–7 mm long, the terminal one subsessile. Calyx lobed to less than half its length. Corolla purplish outside, whitish within and with 2 longitudinal folds on the lower side, 5–8 cm long. Fruit capsule c. 4 cm long, with a wall to 2 mm thick. (Hong et al. 1998).
Distribution China Fujian, Guangdong, Hunan, Zhejiang Taiwan
Habitat Forests below 1200 m; a pioneer tree.
USDA Hardiness Zone 8
RHS Hardiness Rating H4
Conservation status Not evaluated (NE)
Paulownia × taiwaniana was described as a new species in 1975; modern opinion considers it a stable hybrid between P. kawakamii and P. fortunei, artificial hybrids being very similar in appearance. Genetic analysis suggests that P. fortunei was the original seed parent (Xia, Wen & Gao 2019).
This is a more vigorous tree than P. kawakamii, and has been extensively used in forestry plantations around east Asia, although the Taiwanese Paulownia industry was largely destroyed in the 1970s by outbreaks of witches’ broom disease (Yang et al. 2010; Liu et al. 2013). However, like P. kawakamii, it seems to be of limited hardiness (Grimshaw & Bayton 2009), possibly succumbing to as little as 10°C of frost.
Paulownia × taiwaniana remains among the least familiar representatives of its genus in western gardens. Seeds were sent to Kew in 1979 by the Taipei Botanic Garden and the Taiwan Forestry Research Institute (Grimshaw & Bayton 2009), and in 2001 the species was represented here by a two-stemmed tree 12 m tall in woodland shelter by the Cedar Vista. This had died by 2010, but two suckers from its roots had been promoted, growing fast but not always flowering reliably (Grimshaw & Bayton 2009); in 2022 the survivor of these was 16 m × 50 cm dbh (Tree Register 2022). A re-introduction was made early in the 21st century by Bleddyn and Sue Wynn-Jones of Crûg Farm Plants from a wild tree growing at Taroko in eastern Taiwan (BSWJ 7134) (Grimshaw & Bayton 2009), and by 2022 Crûg Farm was offering seedlings from another wild collection, NMWJ 14259, made during a joint expedition with the Taiwan National Museum of Natural Science in 2015 (Crûg Farm Plants 2018). In the cool summers of north-west Wales where this nursery is based, saplings need a warm summer to establish, and are inclined to die back to the base over winter (Grimshaw & Bayton 2009). The tree in the UK National Collection of Paulownia near Bath, planted by David Ewins in 2006 from BSWJ 7134, is the only other established example in the UK known to the author, and had grown to 9 m × 33 cm dbh in 2022 (Tree Register 2022).
There seems remarkably little evidence for the cultivation of Paulownia × taiwaniana elsewhere in the temperate world. Online resources include an image of tree planted in Orlando, Florida, which in a subtropical climate was 9 m tall after just six year and was flowering spectacularly on 29th March 2010. To sound a note of caution, the image’s resolution does not allow the claimed identification to be confirmed.