From the Super Mario Wiki
Rocket Flowers are collectibles that first appear in Super Mario Odyssey. They are very similar to the Turbo Nozzle from Super Mario Sunshine and the Dash Pepper in Super Mario Galaxy 2, in that Mario temporarily gains speed and becomes able to run on water and up walls. The effect wears off once the Rocket Flower's power is exhausted. They appear throughout the Wooded Kingdom after Mario defeats Spewart. They also appear in the Seaside Kingdom, Moon Kingdom, Mushroom Kingdom, and in other kingdoms' bonus rooms.
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