From the Super Mario Wiki
A Sipping Stalk is a bamboo plant found in Wario: Master of Disguise. They are found in Sneezemore Cave. While it may first be seen as a small weed, if water falls on a Sipping Stalk, it will grow into a large vine that Wario can climb. The only way of getting water to land on the Sipping Stalk is by defeating a Snow Globe or Blow Globe when it's right above the stalk.