香柳 (xiāng liǔ), sweet sallow is something I've never come across before and there is little information on it other than that it is a member of the Salix family of plants which includes the willows after which Liuzhou (柳州) is named.
It seems to be added to soups and hotpot or can be briefly stir-fried like any other green.
The taste is initially sweet but turns peppery on the palate. Reminds me a bit of watercress.
It is also, of course, used in TCM.