Abstract: The seeds of five species of Calystegia (C. dahurica, C.hederacea, C.pellita, C.sepium, C.soldanella)in China have been studied under stereoscopic microscope and electron scanning microscope. The results indicate that the seeds are different in size, hilum, ornamentation and protuberance of seed coat, and can be divided into two types:sepium type and pellita type. The sepium type including the first three species is smaller and verrucate, the verrucate protuberance is peaklike, linked together or alone, and has developed from extremely protroding of the intercellular walls of several adjacent testa cells, the ornamentation of seed coat is reticulate; the Pellita type including the other two species is larger and without verruca, and the seed coat ornamentation is ruminate.The morphological characteristic of the seeds are different, and can be used as taxonomic evidence of this genus. The authors consider that the two types of seeds can be used as the foundation for dividing the genus into two section, and the sepium type may be more evolutionary while the pellita type is primitive.

Key words: Calystegia, Seed morphology, Taxonomic significance, China