From the Super Mario Wiki
Nipper Spores are red spheres that are attached to white balls of fluff via small, green stems in Super Mario World 2: Yoshi's Island, Yoshi's Island: Super Mario Advance 3 and Yoshi's Island DS. There are four Nipper Spores on one Nipper Dandelion. When strong gusts of wind blow (usually caused by Windbags), the Nipper Spores are blown off of the Nipper Dandelion and into the air, until they land and become Nipper Plants. No eggs are produced when Yoshi eats a Nipper Spore.