Genus Ipomoea, comprising about 500 species, is the largest genus in Convolvulaceae. The plant species of the genus are distributed across the world's tropical and subtropical regions. Most species are herbs growing either on vines or prostrate, and only a few species are bushes. In particular, from the horticultural point of view, some independent genera are proposed to be separate from the genus Ipomoea. These genera are the morning glory in genusPharbiti, the moonflower in genus Calonyction and the Cypress vine in genus Quamoclit.
The author introduces a classification of Austin (1979, 1980) here. Though his classification study is still under way, we will outline the system here. Austin divided genus Ipomoea into three subgenera and divided each of these into sections.
I. subgenus Ipomoea A. section Ipomoea B. section Pharbitis II. subgenus Quamoclit A. section Mina B. section Calonyction C. section Orthipomoea D. section Dasychaetia E. section Exogonium F. section Batatas III. subgenus Eriospermum A. section Eriospermum B. section Acmostemon C. section Poliothamnus D. section Xerophyta E. section Erpipomoea