Explain the four flower parts
From outside in, it is the sepals, petals, stamens, and pistils. They get closer inward and are higher up from the previous. Having all four means the plant is complete; lacking one or more is incomplete. They can be perfect if they have both stamens and pistils; or, they can be imperfect (staminate or pistillate) if they lack one of the parts. All of these are modified leaves.