A transient occurrence of <i>Ipomoea fimbriosepala</i> (Convolvulaceae) on Gapado Island, Korea

<i>Ipomoea fimbriosepala</i> Choisy (Convolvulaceae) is reported here for the first time from Korea, based on specimens collected on Gapado Island, Jeju-do, in 2021. The species is readily distinguished from related Korean taxa by its unequal sepals, with ovate, abaxially 3-winged outer sepals and smaller, unwinged inner sepals, as well as by its glabrous, sagittate or deltoid leaves. Identification was based on morphological comparisons with the original description, taxonomic literature, and herbarium specimens, and was supported by internal transcribed spacer sequence analysis. Fewer than five individuals were observed within a restricted coastal area, and no additional individuals have been recorded in annual surveys since 2021. The occurrence of <i>I. fimbriosepala</i> on Gapado Island therefore appears to be a transient rather than a self-sustaining population. Given the coastal occurrence on Gapado Island and repeated records from coastal areas of Japan, long-distance dispersal by ocean currents may be a plausible pathway for its occurrence in Korea. A morphological description, illustrations, a key to Korean <i>Ipomoea</i> species, and information on its global distribution are provided.