In botany, a whorl or verticil is an arrangement of leaves, sepals, petals, stamens, or carpels that radiate from a single point and surround or wrap around the stem or stalk. A leaf whorl consists of at least three elements; a pair of opposite leaves is not called a whorl. The morphology of most flowers (called cyclic flowers) is based on four types of whorls: A flower lacking any of these floral structures is said to be incomplete or imperfect. Not all flowers consist of whorls since the parts may instead be spirally arranged, as in the family Magnoliaceae.