Ipomoea hederacea is the most closely related species of Ipomoea nil, the morning glory. Hagiwara (1937) ascertained that both species were crossed at a low rate and F₁ had fertility. Moreover, he found that F₂ plants segregated normally. The hederacea leaf, which is unique to Ipomoea hederacea, is dominant for a round leaf of Ipomoea nil. The author crossbred both species, too, and observed the leaf form in F₁ and F₂ and peroxidase isozymes, and obtained the expected result. Interesting leaf forms were produced when the hederacea leaf form taken into the morning glory was combined with the dragonfly leaf or retracted leaf. However, variation hardly occurred with the flower.

Referrences

1. Hagiwara, T. (1937) On multiple allelomorphs concerning leaf shapes observed in Pharbitis hederacea × P. Nil. Botany & Zoology 5: 2160-2162.
   
2. Yoneda, Y. (1977) Studies on interspecific hybrid in Pharbitis. III. Genetic analyses of leaf shapes and peroxidase isozymes in P. hederacea x P. nil hybrid. Rep. Dept. Lib. Arts, Shizuoka Univ.(Sci.) 13: 43-47.
   
3. Yoneda, Y. and Takenaka, Y. (1981) Natural-color illustrated monograph of Japanese mornig glory. New edition. Hokuryukan, Tokyo.