Factors affecting the velvety outer perianths of Japanese garden iris (Iris ensata Thunb.)

To clarify the factors affecting the velvety outer perianths of Iris ensata, anthocyanins of the perianths and morphology of their epidermis were examined. The studied 2 velvety and 5 non-velvety cultivars were classified in order of major anthocyanins contained: malvidin 3RGac5G-petunidin 3RGac5G and petunidin 3RGac5G-malvidin 3RGac5G. However, there was no relationship between the velvety expression and the type of major anthocyanins. Also, the cultivars have 3 types concerning the perianth epidermal cells such as nipple, round and the intermediate types, and the nipple type does not necessarily induce the velvety perianths. As the results, the correlation of high anthocyanin contents, longer size and high density of epidermal cells of the perianthis was responsible for the velvety expression.