In Russia it is a tradition for astronauts to do what before blasting off into space...

The 'avenue of heroes' at Baikonur in Kazakhstan, where the shuttle will launch, provides a poignant memorial to each mission conducted over the past 50 years. The tradition started with Yuri Gagarin, the first human to enter space, when he planted a single tree before blasting off further from Earth than anyone had ever been. Every Russian cosmonaut, and then later astronauts from other countries, that has left the bounds of Earth from the Cosmodrome has first planted a tree on the path to the launchpad.