I will share the science, publications, and research progress of Yangmei here. 

Why the Tissue Cultured Yangmei liners show the same leaf shape (serrated margin) as seedlings ?

It is normal phenomenal during plant tissue culture, called "Rejuvenation", especially when we do shoot tip culture and subculture many times. On the above pictures, you can see how small the in vitro shoots are, at the beginning, I cut even smaller!!!! The rejuvenation sometimes also happens when you do cuttings or grafting for many generations on some plants. 

There are many books and papers describing the "Rejuvenation" including leaf shape. Here are some: 1] Pierik, R.L.M. (1990). Rejuvenation and Micropropagation. In: Nijkamp, H.J.J., Van Der Plas, L.H.W., Van Aartrijk, J. (eds) Progress in Plant Cellular and Molecular Biology. Current Plant Science and Biotechnology in Agriculture, vol 9. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-2103-0_13 2] Smulders, M.J.M., de Klerk, G.J. Epigenetics in plant tissue culture. Plant Growth Regul 63, 137–146 (2011). https://doi.org/10.1007/s10725-010-9531-4 3]Zhang, Z., Sun, Y. & Li, Y. Plant rejuvenation: from phenotypes to mechanisms. Plant Cell Rep 39, 1249–1262 (2020). https://doi.org/10.1007/s00299-020-02577-1 

You can search more on Google Scholar if you are interested or if you have question why the YANGMEI TC liners are with serrated leaves! This is SCIENCE, not SCAM. 

[1] A great publication on the bioactivities (antioxidant, anti-inflamatory,  anti-allergic, anti-cancer, anti-diabetes, antidiarrheal, and antibacterial acitivity) of Yangmei fruit! The mechanism of so many benefits of yangmei to your health. 

Sun, C., Huang, H., Xu, C. et al. Biological Activities of Extracts from Chinese Bayberry (Myrica rubra Sieb. et Zucc.): A Review. Plant Foods Hum Nutr 68, 97–106 (2013). https://doi.org/10.1007/s11130-013-0349-x 

[2] Yangmei, Chinese bayberry has many cultivars. Dongkui and Biqi are very old and popular cultivars, there are many variations, and sometimes mixed by farmers. This is a paper published on Horticulture Research to explain the genetic relations within different cultivars and relatives species. 

Junke Li, Jun Chen, Luxian Liu, Nan Chen, Xian Li, Kenneth M Cameron, Chengxin Fu, Pan Li, Domestication history reveals multiple genetic improvements of Chinese bayberry cultivars, Horticulture Research, Volume 9, 2022, uhac126, https://doi.org/10.1093/hr/uhac126