27 minutes ago, mgaretz said:@liuzhou What we get in the Asian grocers around here (SF Bay Area) is labeled as Gai Choy and is more compact and curly at the base than what you pictured. Do they have that in China and how is it different than what you posted?
It isn't different. Gai choy (芥菜) is the Cantonese name of what is known in Mandarin as jiè cài.. It is the same plant that I posted - Brassica Juncea.
There are however, several sub-types. There is a reasonable summary here.