The taxonomic status of a new forma, Opuntia humifusa (Raf.) Raf. f. jeollaensis E. J. Kim & S. S. Whang, and the taxonomic relationships of three Korean cladodes were studied based on DNA sequences of three genes. The new forma O. humifusa f. jeollaensis (Wanggasi-Chunnyuncho) is simlilar to O. humifusa (Chunnyuncho), but differ in having both flower with the reddish inner center, and strong and many 3 cm long spines. Molecular studies showed that the new forma grouped into Macrocentra series instead of Humifusa series which included Korean O. humifusa. We designated the new taxa firstly studied here as a new forma, because the taxa have been mainly cultivated in farmlands in Jeolla-do area rather than distributed in nature. The taxonomic relationships of three Korean cladodes are discussed in detail.