From the Super Mario Wiki
A Sproutle Vine is a kind of Beanstalk found in Super Mario Galaxy and Super Mario Galaxy 2. The only difference between a Sproutle Vine and a normal vine is that a normal vine is straight while a Sproutle Vine is twisted. Sproutle Vines often appear after defeating Piranha Plants or breaking open rocks.
To make Mario climb a Sproutle Vine, the player must make Mario jump on a Sproutle Vine and shake the Wii Remote. After Mario gets to the end of the vine, Mario can get off by jumping or just landing on the next planet if there is one.