The Margaret is a plant that can't harm pikmin in any way. They are just in the ground doing nothing, don't mistaken these for a Creeping Chrysanthemum though! These are found in bright areas such as Awakening Wood.
Creeping Chrysanthemum/Taraxacum rovinia
Creeping Chrysanthemums are half plant-animal enemies, much like pikmin. These hide in the floor, they look much like Margarets, the only difrence is you can see there eyes. When you walk over them, they pop out of the floor and try to eat your pikmin!