Campsis is a genus of two species, one native to the United States, the other to China. Both species (and perhaps their hybrid, Campsis x tagliabuana (Vis.) Rehd., even more) are popular garden plants in more temperate areas in Europe (Alexander 2000). In the present account Campsis radicans is accepted in a wide sense as to include hybrids and cultivars.
Alexander J.C.M. (2000) Campsis. In: Cullen J. & al. (eds.), The European Garden Flora, vol. 6. Cambridge University Press, Cambridge: 351-352.
Golliva V. & Giulini P. (1971) Osservazioni sull'ibrido Campsis x tagliabuana (Vis.) Massalongo e sulle sue species genitrici. Giorn. Bot. Ital. 104(6): 469-482.
He S.A., Wu J.Y. & Gu Y. (1990) A study of the relationships of eastern Asian-North American vicarious species in Campsis. Cathaya 2: 21-28.
Wen J. & Jansen R.K. (1995) Morphological and molecular comparisons of Campsis grandiflora and C. radicans (Bignoniaceae), an eastern Asian and eastern North American vicariad species pair. Pl. Syst. Evol. 196(3-4): 173-183.