A small genus of deciduous trees, natives of China, Korea, Indochina, and Formosa, in which six species are recognised by Dr S.-Y. Hu in her monograph (Qtly Journ. Taiwan Mus., Vol. 12 (1959), pp. 1-54). The leading characters are: Bark smooth, branchlets pithy; leaves opposite, entire or lobed; flowers in three- or five-flowered stalked or almost sessile cymes in the axils of the fallen leaves, produced in spring from buds developed in the previous autumn; calyx fleshy, five-lobed; corolla between tubular and funnel-shaped, obscurely two-lipped, the upper lip two-lobed, the lower three-lobed; stamens four; style one, with a small stigma; capsules ovoid to ellipsoid, with numerous winged seeds.
Dr Hu follows Pennel in retaining Paulownia in Scrophulariaceae as a monotypic tribe. Other botanists have placed it in the Bignoniaceae and indeed it bears a very close resemblance to Catalpa, which certainly belongs to the latter family. However, the Bignoniaceae and Scrophulariaceae are closely allied, and it has been suggested that Catalpa and Paulownia are near to the ancestral stock from which the two families have branched. The most obvious differential character of the catalpas is that their trunks are rugged and that the flowers are borne in summer at the ends of the seasonal growths; they also differ markedly from any paulownia in their long, cylindrical fruits.
The genus was named by Siebold in honour of Anna Paulowna, Hereditary Princess of the Netherlands.
For propagation and cultivation, see under P. tomentosa.