Diagram showing the parts of a mature flower. In this example the perianth is separated into a calyx (sepals) and corolla (petals)
A tepal is the term used to identify one of the outer parts of a flower (collectively the perianth) when these parts cannot easily be divided into two kinds, sepals and petals. This may be because the parts of the perianth are undifferentiated (i.e. of very similar appearance), as in Magnolia, or because, although it is possible to distinguish an outer whorl of sepals from an inner whorl of petals, the sepals and petals are similar in appearance to one another (as in Lilium). The term was first proposed by Augustin Pyramus de Candolle in 1827.[1][2] (De Candolle used the term perigonium or perigone for the tepals collectively; today this term is used as a synonym for "perianth".[3])
A
Lilium flower showing the six
tepals: the inner three are petals and the outer three are sepals.
Undifferentiated tepals are believed to be the ancestral condition in pollinators.
Tepals formed by similar sepals and petals are common in
In some plants the flowers have no petals, and all the tepals are sepals modified to look like petals. These organs are described as petaloid, for example, the sepals of hellebores. When the undifferentiated tepals resemble petals, they are also referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly coloured tepals. Since they include Liliales, an alternative name is lilioid monocots.
Properties
Terms used in the description of tepals include pubescent (with dense fine, short, soft hairs, downy), puberulent (minutely pubescent, hairs barely visible to the naked eye) and puberulous (dense covering of very short soft hairs).
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Flowers with tepals
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A tulip flower showing the petal-like tepals
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A hellebore flower showing the petaloid sepals
See also
References
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^ Augustin Pyramus de Candolle (1827). Organographie végétale, ou Description raisonnée des organes des plantes; pour servir de suite et de développement a la théorie élémentaire de la botanique, et d'introduction a la physiologie végétale et a la physiologie végétale et a la description des familles. Paris: Deterville. p. 503.
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^ Augustin Pyramus de Candolle (1841). Vegetable organography; or, An analytical description of the organs of plants 2. translated by Boughton Kingdon. London: Houlston & Stoneman. p. 90.
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^ Stearn, William Thomas (2004). Botanical Latin (p/b ed.). David & Charles/Timber Press. p. 39.
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^ Ronse De Craene, L. P. (2007). "Are Petals Sterile Stamens or Bracts? The Origin and Evolution of Petals in the Core Eudicots". Annals of Botany 100 (3): 621–630.
Botany: A Brief Introduction To Plant Biology - 5th ed. Thomas L. Rost; T. Elliot Weier - Wiley & Sons 1979 ISBN 0-471-02114-8.
Plant Systematics - Jones; Samuel - McGraw-Hill 1979 ISBN 0-07-032795-5.
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