Ornamental crabapples are a general term for a group of plants in the genus Malus (Rosaceae) with small fruit sizes (usually fruit diameter ≤ 5 cm), and mostly small trees (Zhou et al. 2018). Since the Han Dynasty, ornamental crabapples have been cultivated and used in landscape and gardens in China. They were widely eulogized by literatus and were once referred to as “the fairy of flowers” (Zhou et al. 2018). Chinese ornamental crabapples were introduced to North America in the second half of the 18th century and then to Europe in the 19th century (Wang 2014). During more than 200 years, a large number of excellent new cultivars of ornamental crabapples have been cultivated through complicated hybridization and selection work (Zhou et al. 2018). Ornamental crabapples breeding in China started relatively late, and the main ornamental crabapple cultivars were introduced from North America and Europe, but with the rapid development of ornamental horticulture cultivation research in China in recent years more and more new cultivars of excellent ornamental crabapples are being introduced to the market, including ‘Yangzhi Yu’ (Jiang et al. 2020), ‘Er Qiao’ (Yang et al. 2022), ‘Yi Honglian’ (Zeng et al. 2022), and ‘Fenghong Nichang’ (Fan et al. 2019). Although there is no shortage of semiheavy petal types, double flowers are still extremely uncommon. It is of great significance to vigorously cultivate new crabapple species with a high degree of double petals, novel flower shape, and good stability and ornamental properties. The elite cultivars also enrich the diversity of crabapples and make up better flowering plant combinations in garden designs.
Yun Xiangrong [Note: from 《Qingping Tune》made by Li Bai, a poet of the Tang Dynasty, mostly describing the richness of posture, rich and luxurious] (Ke 2017) is a new cultivar selected and released by Nanjing Forestry University. It is an excellent light-colored double-flowered crabapple cultivar with large flower buds (1.5–1.9 cm in diameter larger than ‘Van Eseltine’ 1.2–1.4 cm in diameter).
Agricultural Research Service, US Department of Agriculture 2012 USDA plant hardiness zone map Agricultural Research Service, US Department of Agriculture USA
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