seeing someone off with an osier is a chinese tradition. and popularly it was considered to have some relation with a homonymic phenomenon between the 「liu( osier )」 and 「liu(stay)」.
中国有悠久的折柳送别传统,对于这一民俗形成缘由解释较为纷繁,一般认为以「柳」谐「留」,是谐音现象。
that day, accidentally, i saw a net friend's poster about seeing someone off at the airport, touching indeed.