It was very difficult to cross Ipomoea hederacea with Ipomoea purpurea. In 1980 the author collected a lot of strains of both species each and crossbred them on a large scale, but obtained only one seed after about 2000 crossings. From that single seed, the author was able to bring up an F₁ plant, which set seeds. So F₂ descendants were grown.

Slide No. 214-220
Akamaruzaki Red round flower	Usuakamaruzaki Light red round flower	Aomurasakimaruzaki Bluish purple round flower	Koimurasakimaruzaki Dark purple round flower
Koimurasakimaruzaki Dark purple round flower	Koiaomurasakimaruzaki Dark bluish purple round flower	Koiakamaruzaki Dark red round flower

References

1. Yoneda, Y. and Takenaka, Y. (1981) Natural-color illustrated monograph of Japanese mornig glory. New edition. 74th Plate 201 Figure, Hokuryukan, Tokyo.
   
2. Yoneda, Y. & Tamaki, S. (1984) Studies on interspecific hybrid in Pharbitis. VI. A hybrid of P. hederacea x P. purpurea and its descendants. Rep. Fac. Lib. Arts, Shizuoka Uni. (Sci.) 20: 9-17.