Crabapples are ornamental apples that belong to genus Malus of the Rosaceae family (International Union for the Protection of New Varieties of Plants, 2003). They are shrubs or small trees that produce fruit with a diameter ≤5.1 cm (2 inches), and are important ornamental trees in temperate zones because of their excellent floral displays (flower type, diameter, shape, and color), colorful fruit (shades of lime green, amber, gold, yellow, orange, red, and purple), wide range of growth habits (drought resistance, cold resistance, saline alkali tolerance, barren resistance), and potential for attracting wildlife (Dirr, 2010).
After more than 300 years of hybridization and cultivar introduction in the United States, Europe, and Asia, there are ≈1200 crabapple varieties, with about 100 commonly supplied in today’s global market. Unfortunately, double-petal varieties of flowering crabapples are relatively scarce (Fiala, 1994). In the past 20 years, only two new double-flower crabapple cultivars—Spring Bride and Jarmin—have been released into the U.S. market (Fan et al., 2019).
In traditional Chinese culture, double-petal flowers represent elegance, beauty, and generosity. The Chinese double-flowering crabapple Malus spectabilis ‘Plena’ has been incorporated into landscapes since the mid-1700s (Romer, 2002). There are rich crabapple germplasm resources in China, and more attention has been paid to breeding varieties of crabapple in recent years. New varieties have been introduced continuously (Zhou et al., 2019), and the ornamental characteristics of the leaves, fruit, flowers, and colors have gradually diversified (Li, 2012; Li et al., 2008; Zhang et al., 2020).
Natural hybridization is significant for species evolution as heteropolyploid progeny are competitive and adaptable (Krystyna et al., 1997; Prentis et al., 2008). Malus ‘Xiang He’ was selected by natural hybridization and released from the Shandong Provincial Academy of Forestry’s crabapple program, which started in 1999. The cultivar has significant ornamental features in the form of double, red–purple flowers with a diameter of 5.5 to 6.5 cm (blooms between mid-April and early May), and small red fruit with a long bearing period (until early March of the following year). The cultivar also displays strong adaptability and resistance to diseases and pests in Shandong Province, China.
Dirr, M. 2010 Manual of woody landscape plants. 6th ed. Stipes Publishing, Champaign, IL
Fan, J., Zhang, W., Zhang, D., Zhou, T., Jiang, H., Wang, G. & Cao, F. 2019 ‘Fenghong Nichang’ flowering crabapple HortScience 54 1260 1262 doi: 10.21273/HORTSCI13897-19
Fiala, J.L. 1994 Flowering crabapples: The genus Malus, p. 106–273. Timber Press, Portland, OR
Hu, D., Han, Y., Xu, J., Wang, L., Zhu, S. & Dun, X. 2018 A new ornamental crabapple cultivar ‘Changhui’ Acta Hort. Sinica 45 S2 389 391 doi: 10.16420/j.issn.0513-353x.2018–0403
International Union for the Protection of New Varieties of Plants. 2003 Guidelines for the conduct of tests for distinctness uniformity and stability [ornamental apple (Malus Mill.)]. TG/192/1
Krystyna, M.U., Hurka, H., Landolt, E., Neuffer, B. & Mummenhoff, K. 1997 Hybridization and evolution in Cardamine L. (Brassicaceae) at Urnerboden, Central Switzerland: Biosystematic and molecular evidence Plant Syst. Evol. 204 3–4 389 391 doi: 10.1007/BF00989208
Li, H. 2012 Studies on the taxonomy of the genus Malus Mill. (Rosaceae) of Taiyi-Mountains candidate. Shenyang Agricultural University, Shenyang, China
Li, X., Shen, X., Sun, F., Shu, H., Guo, L. & Cao, Y. 2008 Ornamental crabapple pollen morphology and its taxonomic applications Acta Hort. Sinica 35 8 389 391 doi: 10.16420/j.issn.0513-353x.2008.08.015
Prentis P.J., Wilson, J.R.U., Dormontt, E.E., Richardson, D.M. & Lowe, A.J. 2008 Adaptive evolution in invasive species Trends Plant Sci. 13 6 389 391 doi: 10.1016/j.tplants.2008.03.004
Romer, J.P. 2002 A survey of selection preferences for crabapple cultivars and species. Retrospective Theses and Dissertations. 17559. <https://lib.dr.iastate.edu/rtd/17559>
Royal Horticultural Society 2007 RHS color chart. 5th ed. Royal Horticultural Society, London, UK
Zhang, L., Mao, Y., Wang, Y., Wang, L., Yin, Y. & Shen, X. 2020 Malus spectabilis ‘Duojiao’: A new yellow-leaf cultivar HortScience 55 1155 1158 doi: 10.21273/HORTSCI14865-20
Zhou, T., Jiang, H., Zhang, D., Fan, J., Zhang, L., Wang, G., Zhang, W. & Cao, F. 2019 ‘Fen Balei’ crabapple HortScience 54 1433 1434 doi: 10.21273/HORTSCI14063-19
Zhou, T., Jiang, H., Zhang, W., Zhang, D., Fan, J., Zhang, Q., Wang, G. & Cao, F. 2020 ‘Zi Dieer’ crabapple HortScience 55 272 274 doi: 10.21273/HORTSCI14590-19