Basic definition: tree: stand; banner: flag. To raise a flag alone. It is a metaphor for being unique and novel, forming a family of one's own.

Origin: Yuan Mei (清-袁枚)《随園诗话》："That is why it can stand alone; it is precisely because it does not follow the pattern of the Shengtang."

Near synonyms: to be new and different, to be self-contained, to be unique, to innovate, to lead a different standard, to be unique.