<P> A sepal (/ ˈsɛpəl / or / ˈsiːpəl /) is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom . The term sepalum was coined by Noël Martin Joseph de Necker in 1790, and derived from the Greek σκεπη (skepi), a covering . </P> <P> Collectively the sepals are called the calyx (plural calyces), the outermost whorl of parts that form a flower . The word calyx was adopted from the Latin calyx, not to be confused with calix, a cup or goblet . Calyx derived from the Greek κάλυξ (kalyx), a bud, a calyx, a husk or wrapping, (cf Sanskrit kalika, a bud) while calix derived from the Greek κυλιξ (kylix), a cup or goblet, and the words have been used interchangeably in botanical Latin . </P> <P> After flowering, most plants have no more use for the calyx which withers or becomes vestigial . Some plants retain a thorny calyx, either dried or live, as protection for the fruit or seeds . Examples include species of Acaena, some of the Solanaceae (for example the Tomatillo, Physalis philadelphica), and the water caltrop, Trapa natans . In some species the calyx not only persists after flowering, but instead of withering, begins to grow until it forms a bladder - like enclosure around the fruit . This is an effective protection against some kinds of birds and insects, for example in Hibiscus trionum and the Cape gooseberry . </P> <P> Morphologically, both sepals and petals are modified leaves . The calyx (the sepals) and the corolla (the petals) are the outer sterile whorls of the flower, which together form what is known as the perianth . </P>

By definition a fruit is derived from the archegonium. corolla. calyx. ovary. stamen