Sepal

A sepal is one member or part of the calyx of a flower; it is the outer part of the perianth. The perianth comprises the sterile parts of a flower, consisting of inner and outer tepals that are usually differentiated into petals and sepals. The term tepal is usually applied when the petals and sepals are not differentiated. In a "typical" flower the sepals are green and lay under the petals, but there is considerable variation in form among the flowering plants.