tepals

Tepals are the parts of a flower’s perianth when the outer organs (sepals) and inner organs (petals) are not easily distinguishable by appearance or function. The term tepal combines petals and sepals and is used for flowers in which the perianth segments are similar in size, shape, and color, making it difficult to separate them into distinct calyx and corolla.

Tepals are common in many monocot flowers. In lilies (Lilium), tulips (Tulipa), and related groups, the six perianth segments are alike in form, so the outer and inner whorls are collectively described as tepals rather than as separate sepals and petals. The concept is also applied to other flowers with petaloid perianth segments, such as many orchids and iris relatives, where the perianth parts are not readily categorized as true petals or true sepals.

In contrast, flowers with clearly differentiated sepals and petals are described using those terms rather than tepals. The use of tepals is a descriptive convention in plant morphology and systematics to reflect a lack of distinction between perianth parts rather than a strict anatomical division.

Examples of plants typically described as having tepals include many lilies and tulips, as well as various monocot groups such as Allium species. The term helps clarify perianth structure in flowers with undifferentiated or highly similar perianth segments and is less applicable to flowers with distinct calyx and corolla.