The peanut is different because it flowers above the ground, but fruits below the ground.
The Peanut seeds (kernels) grow into a green oval-leafed plant about 18 inches tall with flowers around the bottom of the plant. The flowers lose their petals and the peanuts begin to grow. The "peg" (the peanut) grows down away from the plant, forming a small stem, which digs into the soil. The Peanut is at the tip of the peg.  In about 4-5 months, you will have peanuts under the ground.