Abstract: The excised stem-tips of the germinating tubers of Stachys sieboldii Miq. were cultivated under the laboratory condition. As the room temperature decreased, the formation of tubercles on the tips of the explanted stems was observed. The excised tips of the rhizome at its different stages of development, when cultured in vitro, demonstrated variations in tuber formation. When the excised tips were taken from the rhizomes which had just emerged from the base of the aerial shoots, they usually failed to grow. However, existence of normal growth was observed in the cultured excised tips of the rhizomes that had become elongated at which time flowering occurred on the aerial shoot. The tips became swollen as the environmental temperature decreased. In early September, as the process of underground tuberization initiated, cultures taken from the nontuberized tips again grew poorly and usually failed to form tubercles.