Loropetalum chinense, is a popular ornamental shrub known for its distinctive flowers and foliage color. Due to its aesthetic appeal and adaptability, Loropetalum is widely used in landscaping and has become an important crop for U.S. nurseries. However, limited understanding of genetic diversity among cultivars presents challenges for breeding efforts, as genome size and ploidy levels play a crucial role in hybridization success and in determining phenotypic traits such as flower size, color, and plant vigor. This study aimed to measure the ploidy levels and relative genome sizes of a wide range of Loropetalum cultivars in the U.S. to inform future breeding strategies. Flow cytometry was used to determine genome size and estimated ploidy, and chromosome countings were performed to validate the ploidy data. A total of 33 accessions were inspected, with 32 found to be diploids and one triploid. The 1Cx genome size ranged from 2.42 to 3.06 pg across cultivars. These results provide a foundational knowledge on ploidy and genome size variation in the Loropetalum germplasm that would benefit future Loropetalum breeding decisions.
