This is the commonly cultivated "morning-glory" from tropical America. It is often escaped and locally weedy. The first report of wild plants from Ky. was in 1914 (Gm). There are varied color forms, and plants with lobed leaves have been occasionally reported in other states (Cr, Y). Several other related species from warmer regions are sometimes cultivated. These include I. lobata (cerv.) Thell. ("firecracker vine") and I.. tricolor Cav., which originates from Central America and may be locally escaped in southeastern states (K, Y). I. tricolor can be confused with purpurea, but differs in its glabrous sepals and pedicels (versus conspicuously pubescent) and its 2-lobed stigmas (versus 3-lobed); it is probably closer to pandurata (Y). Ergoline alkaloids are not confirmed in purpurea, but have been reported from this species based on confusion with tricolor, a species from Central America that is usually alkaloid-positive (Meira et al. 2012, Wood et al. 2020, Beaulieu et al. 2021). Production of these alkaloids has been linked with the fungal endosymbiont, Periglandula; root-knot nematodes are reduced by these chemicals (Durden et al. 2019).