This study was conducted to demonstrate the seasonal change of floral organ number and morphology, and the effect of growth temperature on floral morphology in double-flowered cyclamen with petaloid-stamens. In plants grown under seasonal variable temperature, floral organ number and morphology in petaloid-stamen type of double flower changed as time passed, but the degrees of such changes differed depending on the line; there were two types, namely, “variable” and “relatively stable”, in terms of the number of outer and inner petaloid-stamens throughout the flowering period. In the plants grown under different constant temperatures, the rate of complete petals (petaloid-stamens) to the total organs in whorl 3 was greatest at 15°C, followed by the values at 25°C and 20°C. In contrast to complete petals, the rate of incomplete petals (petaloid-stamens) to the total organs in whorl 3 was greatest at 20°C, followed by the values at 25°C and 15°C. The rate of stamen-like organs to the total organs in whorl 3 did not differ significantly among treatments, and the rate of stamens to the total organs in whorl 3 was suppressed only at 25°C. Although the total numbers of stamens and stamen-like organs were similar at 15°C and 20°C, the developed positions of stamen-like organs and stamens were significantly different between 15°C and 20°C. Additional organs including stamens were produced inside the petaloid-stamen at 15°C, while restoration of the stamen was induced at 20°C. In conclusion, floral morphology shows seasonal change, and growth temperature affects the petaloidy of stamen in double-flowered cyclamen. However, the effect on petaloidy differs according to the line.