The sweet potato, the water spinach and the moonflower are famous members of the morning-glory genus. Together with some 800 other species, these plants all belong to the megadiverse genus Ipomoea, the largest genus in the family Convolvulaceae.
Ipomoea includes herbs, shrubs, lianas and trees and is present in all tropical and subtropical regions of the world, from sea level to 4,000 metres and from tropical rain forests to semi-desert coastal environments. The genus is also present in other more temperate regions as far north as Canada, whilst several widespread species have a worldwide distribution. Around two thirds of the currently recognised species are distributed in the Americas and the other third are naturally distributed in the Old World. Recent taxonomic studies have dramatically improved our knowledge of the genus, albeit new species from all around the world are still described every year. Moreover, many of these species are only known from a few specimens or populations.
The name Ipomoea derives from the Greek ips, ipos (worm or woodworm) and hómoios (resembling), for the apparent similarity of the twining stems of many species to these animals.
Two species have global importance as crops: the kang-kong or water spinach (Ipomoea aquatica Forssk.) and, of course, the sweet potato (Ipomoea batatas (L.) Lam.). Sweet potato is among the most widely consumed crops in the world and a staple in many countries. A crop of American origin (although where in the American continent is still a matter of discussion), the archaeological record suggests it could have been cultivated by pre-Incan cultures in Peru as early as 8,000 years BCE, but certainly at least 3,000 years BCE. Also, sweet potatoes may have been one of the first American crops to arrive in Europe. They are thought to have arrived in Europe onboard Columbus’ vessels upon their return from the first voyage to the New World in 1492; there are records of the species’ cultivation in southern Spain just one year later – in 1493.
In addition to the edible species, several other Ipomoea species are cultivated in gardens for their colourful flowers – the familiar morning glories. Other species have become invasive in different parts of the world, for example Ipomoea cairica (L.) Sweet, Ipomoea indica (Burm.) Merr., Ipomoea purpurea (L.) Roth and the moonflower, Ipomoea alba L. In addition, multiple studies have identified anti-tumorous properties associated with different compounds obtained from Ipomoea leaves and roots.
Muñoz-Rodríguez, PM, Carruthers, T, Wood, JRI, Williams, BRM, Weitemier, K, Kronmiller, B, Goodwin, Z, Sumadijaya, A, Anglin, NL, Filer, D, Harris, D, Rausher, MD, Kelly, S, Liston, A and Scotland, RW 2019. A taxonomic monograph of Ipomoea integrated across phylogenetic scales. Nature Plants 5: 1136-1144.
Wood, JRI, Muñoz-Rodríguez, P, Williams, BRM and Scotland, RW 2020. A foundation monograph of Ipomoea (Convolvulaceae) in the New World. Phytokeys 143: 1-823.