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– Etymology:
– Term “sepalum” coined by Noël Martin Joseph de Necker in 1790
– Derived from Ancient Greek “σκέπη” (sképē) meaning “covering”
– Sepals collectively called the calyx (plural: calyces)
– Word “calyx” adopted from Latin, not to be confused with “calix” meaning cup or goblet
– Latin “calyx” derived from Greek “κάλυξ” (kalyx) meaning bud, calyx, husk

– Description:
– Term “tepal” used when perianth parts are hard to distinguish
– Tepals referred to as petaloid when resembling petals
Flower merosity indicates plant classification
– Sepals may be free (polysepalous) or fused together (gamosepalous)
– Sepals’ development and form vary among flowering plants

– Morphology:
– Sepals and petals are modified leaves
– Calyx and corolla are outer sterile whorls forming the perianth
– In some plants like Aristolochia, calyx is primary whorl with large sizes

– Function:
– Sepals can perform photosynthesis like ordinary leaves
– Sepals have lower stomatal density, limiting gas exchange compared to leaves
– Calyx withers after flowering in most plants
– Some plants retain thorny calyx for protection
– Calyx can grow into an accessory fruit in some species

– See also:
– Wikimedia Commons has media related to Sepals
– Information on “petal” from Oxford Languages
– Definition of “sepal” from
– Reference to “The Kew Plant Glossary” by Henk Beentje
– Various sources and references on botany and plant morphology

Sepal (Wikipedia)

A sepal (/ˈsɛpəl, ˈspəl/) 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.

Diagram showing the parts of a mature flower. In this example, the perianth is separated into a calyx (sepals) and corolla (petals)
Tetramerous flower of Ludwigia octovalvis showing petals and sepals.
After blooming, the sepals of Hibiscus sabdariffa expand into an edible accessory fruit
In many Fabaceae flowers, a calyx tube surrounds the petals.
The large calyx of the medlar fruit is the source of its vulgar nicknames.
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