Nice trees Junmilo
Evergreen gardenworks has a bunch of named varieties. Not sure if it will help identify yours but it's worth a look..
https://www.evergreengardenworks.com/prunus.htm
Brent is the only place I know in the US selling ungrafted mume. I only have two that I have been growing out for years but so far they have been relatively easy. grow like weeds and trunk up quickly and to me they are the best flowering species for bonsai. Azalea make a bold show, but i find something about the delicate flowers of mume a little more appealing. I've already placed my order from him for some more! Get em before they are gone!
