The willow branch (柳树枝) is a part of the willow tree. In ancient China, willow branches were often used as a parting gift between friends and family (member). Even today, willow branches (mention) in many cases as a symbol of saying goodbye. Do you know ?
One reason is that willow trees are strong. They can live (easy) in any place, wet or dry, north or south. Because of this, giving a willow branch to say goodbye to loved ones is a way to tell them you hope they will get used to (they) new living environment.
For another reason, the pronunciation for the willow tree "liu (柳)" is similar the character "liu (留)" in Chinese, which means inviting someone (stay) —only the tones are different. So (offer) a willow branch means asking the other party to live for a longer time, even though we know that they must leave.
It's said that this custom became popular during the Han Dynasty. At that time, Baqiao, a bridge in Chang'an, today's Xi'an, was common place to say goodbye. People often (stop) there and handed willow branches to people who were leaving.