HortScience (Jan 2023)
Daparo: A New Blue Cultivar of Iris ensata Thunb.
Abstract
Iris is one of most famous ornamental plants in the world, and it is the largest genus in the family Iridaceae. The genus Iris comprises ∼280 species (Goldblatt and Manning 2008). There are ∼70,000 known cultivars, which can be mainly divided into bearded irises and beardless irises according to the appendants of the outer petals (Hu and Xiao 2012). As an outstanding group of beardless irises, Japanese irises are traditional plants with a history longer than 500 years in Japan, and they have been exported to the United States since the 1890s (Xiao and Hu 2018). With graceful leaves and colorful flowers, Japanese irises are popular worldwide. They bloom in early summer (May to mid-June in Eastern China). These irises can be grown in US Department of Agriculture Zones 4 to 9. They grow best in full sunlight with sufficient irrigation, and they are usually grown in oriental gardens, theme gardens, water gardens, and containers. Japanese irises have been artificially selectively bred from Iris ensata Thunb. in Japan since the late 1600s (Xiao and Hu 2018). There are ∼5000 cultivars of Japanese iris. I. ensata belong to the subgenus Limniris section Limniris Taush. (Wilson 2006; Zhao et al. 2000). This species is native to eastern China, northeast of China, eastern Russian, the Korean peninsula, and the islands of Japan (Xiao et al. 2015). Japanese irises have varied flower forms, including double, half-double, and single flowers. They also have the most diverse flower color patterns among all irises, including the self pattern, vein pattern, halo pattern, rimmed pattern, and brushed pattern (Xiao and Hu 2018). Consumers prefer a flower pattern in which the veins are lighter than the background color in the fall. The common flower colors of Japanese iris are purple, bluish violet, red-violet, and white, but there is a serious shortage of Japanese irises with true blue flowers. During the 1960s to 1980s, Shuichi Hirao generated a series of Japanese irises with flowers close to true blue, including I. ensata ‘Aizoshi’, I. ensata ‘Asa To Biraki’, I. ensata ‘Hekiho’, and I. ensata ‘Izu No Umi’ by using the old cultivar I. ensata ‘Asazumabune’ as parents. During the 1980s and 1990s, breeders at Kamo Garden in Shizuoka Prefecture, Japan, produced several Japanese iris cultivars with blue flowers, including I. ensata ‘Ogi No Mato’, whose flowers had white veins on blue petals. More recently, breeders in the United States generated some excellent blue Japanese irises, such as I. ensata ‘Lake Effect’, I. ensata ‘Banjo Blues’, and I. ensata ‘Koto Harp Strings’ (Mt. Pleasant Iris Farm 2015). Here, we describe a new Japanese iris cultivar that produces attractive blue flowers with white veins. This cultivar was obtained by hybridization in 2018 at the Shanghai Botanical Garden. It flowers from early May to mid-May in Shanghai, China.
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