In some flowers, the pieces of the chalice and the corolla can not be differentiated or, what is the same thing, can not be determined if they are petals or sepals (that is to say, all the pieces of the sterile cycles of the flower are equal to each other). This cycle is called perigon (peri, 'around', gonio, 'structures of reproduction') and the parts that compose it are called Tepals. If the tepals resemble a petal, the perigon is called "corolino" (corolla); if they resemble sepals, it is said "Calico perigon" or "calicoid." Perigon (cream) and paraperigony (yellow) in Narcissus Flower of Hymenocallis speciosa, the paraperigonium or staminal crown can be observed joining the filaments of the six stamens. Paraperigonio
Each petal or tepalo that forms the corolla is formed by a "nail" that fixes it to the receptacle and by a "limbo" that is the widened and generally showy part of the corolla. In certain genera (Narcissus), for example, in the upper part of the nail there is a ligular appendage forming a cup within the cycle of tepals called "paraperigonium" or "false corolla". In other cases -Hymenocallis- paraperigonio is constituted by a membrane that unites the filaments of the stamens. In the latter case the paraperigonium is also called the "stem crown". Bibliography
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