Dormancy and morphological characteristics of the non-harsh tasting line of Japanese bracken (Pteridium aquilinum Kuhn) were investigated. Color of new bud in the harsh-tasting line was pale green, whereas that of the non-harsh tasting line was purplish green. Trichome density of new buds in the non-harsh tasting line was higher and the starting period of bud emergence was about 9 days later than those of the harsh tasting line. To examine the dormancy, the effect of starting time of warming treatment on bud break was investigated. The rhizomes of the nonharsh tasting line grown at an altitude of around 703 m were warmed at minimum temperature of 15°C. Bud break occurred when the treatment was started after November 27. To examine the effect of low temperature on breaking of dormancy, the rhizomes which were harvested on October 30, were treated at either 5 or 10°C. The treated period at each plots were for 10, 20, and 30 days. After low temperature treatment, the rhizomes were warmed at minimum temperature of 16°C. Bud break occurred in the rhizomes only when they were treated by more than 20 days of less than 10°C.