Capsicum species consist of five cultivated species, C. annuum, C. baccatum, C. chinense, C. frutescens and C. pubescens. Among these five cultivated Capsicum species, C. pubescens (rocoto) has morphological characteristics that are very different from those of other Capsicum species, such as purple flowers, fine pubescence on stems and leaves, bright red, orange or yellow mature fruits, black seeds, and bell-shaped fruits that resemble bell peppers. Rocoto is a pepper cultivated in high altitude regions from Mexico to Peru, with its origins in the Andes of Peru and Bolivia. It is cultivated as a perennial plant in these regions, and is said to grow into a bush with a height of more than 2 m. Rocoto is considered to be one of the oldest cultivated plants in the Americas, having been cultivated since around 6000 BC. When rocoto is grown in an open field in Japan, it flowers but does not bear fruit. The fruiting difficulty of rocoto was investigated, and it was found that this species is a self-incompatible pepper that does not self- fruit by self-pollination. Colchicine treatment of rocoto seeds yielded tetraploids, which were self-fertile. The maximum leaf width and petal length of tetraploid loci were significantly larger than those of diploids, and the number of petals was around 6 in diploids, whereas most tetraploids had 7 to 8 petals. Pollen grain size was also significantly larger in tetraploids than in diploids. Fruit size was not significantly different between diploids and tetraploids, but tetraploids tended to have slightly thicker fruit flesh. Unlike "Taka-no-tsume", which is mainly composed of capsaicin in Japan, rocoto is a hot pepper characterized by its stimulating spiciness that hits the back of the throat, mainly from its dihydrocapsaicin content. It is said that the higher the dihydrocapsaicin content, the less sharp and pungent the taste becomes, and the pungent taste lingers in the mouth, making it undesirable. However, the "lingering spiciness" of rocoto may become a new attraction in the recent boom in hot peppers.