Copyright 1998-2017 Yoshiaki Yoneda
While the morning glories belong to the tribe Ipomoeeae, genus Calystegia is classified in a different tribe, Conovolvuleae. We can find Calystegia japonica and C. soldanella nearby, which continue blooming in hot sunlight, whereas the flowers of the morning glories wither up early in the morning. We are very much interested in the contrastive character of the flower petals. From this flower petal withering point of view,, the author took up genus Calystegia as a member of the same Convolvulaceae. Furthermore, we were able to produce interspecific hybrids among Calystegia species, so these results were presented. The author hopes these plants will be useful as study materials.
As for the genus Calystegia, about 25 species are distributed over temperate to tropical zones throughout the world, among which four species grow wild in Japan. I introduced three species among the plants of Convolvulaceae already. These plants are perennial, have vines and prostrate stems, and their underground stems are very well developed. A remarkable characteristic of Calystegia is its two pieces of big bracts, which cover the calyx.