One of the layers of modified leaves that make a flower; a complete flower has four whorls: sepals, petals, stamens, and pistil from base to top. See also: sepal, petal, stamens, pistil.
Photo: Sue Bergeron, used with permission
Daylily flower with some petals and sepals removed to show the four floral whorls. Frontal view below.
Photo: Pat Loveland, used with permission