A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or 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 have similar appearance to one another (as in Lilium). The term was first proposed by Augustin Pyramus de Candolle in 1827 and was constructed by analogy with the terms "petal" and "sepal".[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]
Diagram showing the parts of a mature flower. In this example the perianth is separated into a calyx (sepals) and corolla (petals)
A Lilium flower showing the six tepals: the outer three are sepals and the inner three are petals.
Undifferentiated tepals are believed to be the ancestral condition in flowering plants. For example, Amborella, which is thought to have separated earliest in the evolution of flowering plants,[4] has flowers with undifferentiated tepals. Distinct petals and sepals would therefore have arisen by differentiation, probably in response to animal pollination. In typical modern flowers, the outer or enclosing whorl of organs forms sepals, specialised for protection of the flower bud as it develops, while the inner whorl forms petals, which attract pollinators.
Tepals formed by similar sepals and petals are common in monocotyledons, particularly the "lilioid monocots". In tulips, for example, the first and second whorls both contain structures that look like petals. These are fused at the base to form one large, showy, six-parted structure (the perianth). In lilies the organs in the first whorl are separate from the second, but all look similar, thus all the showy parts are often called tepals. Where sepals and petals can in principle be distinguished, usage of the term "tepal" is not always consistent – some authors will refer to "sepals and petals" where others use "tepals" in the same context.
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 and shape
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). Tepal shape is described in similar terms to those used for leaves (see Glossary of leaf morphology).
Gallery
Flowers with tepals
Flowers of Magnolia × alba showing tepals in various stages of development
^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.
^Augustin Pyramus de Candolle (1841). Vegetable organography; or, An analytical description of the organs of plants. Vol. 2. Translated by Boughton Kingdon. London: Houlston & Stoneman. p. 90.
^Stearn, William Thomas (2004). Botanical Latin (p/b ed.). David & Charles/Timber Press. ISBN978-0-7153-1643-6. p. 39.
^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. doi:10.1093/aob/mcm076. PMC2533615. PMID 17513305.
Botany: A Brief Introduction To Plant Biology - 5th ed. Thomas L. Rost; T. Elliot Weier - Wiley & Sons 1979 ISBN0-471-02114-8.
Plant Systematics - Jones; Samuel - McGraw-Hill 1979 ISBN0-07-032795-5.
January 13, 2023
tepal, tepal, outer, parts, flower, collectively, perianth, term, used, when, these, parts, cannot, easily, classified, either, sepals, petals, this, because, parts, perianth, undifferentiated, very, similar, appearance, magnolia, because, although, possible, . A tepal is one of the outer parts of a flower collectively the perianth The term is used when these parts cannot easily be classified as either sepals or 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 have similar appearance to one another as in Lilium The term was first proposed by Augustin Pyramus de Candolle in 1827 and was constructed by analogy with the terms petal and sepal 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 Diagram showing the parts of a mature flower In this example the perianth is separated into a calyx sepals and corolla petals Contents 1 Origin 2 Properties and shape 3 Gallery 4 See also 5 ReferencesOrigin Edit A Lilium flower showing the six tepals the outer three are sepals and the inner three are petals Undifferentiated tepals are believed to be the ancestral condition in flowering plants For example Amborella which is thought to have separated earliest in the evolution of flowering plants 4 has flowers with undifferentiated tepals Distinct petals and sepals would therefore have arisen by differentiation probably in response to animal pollination In typical modern flowers the outer or enclosing whorl of organs forms sepals specialised for protection of the flower bud as it develops while the inner whorl forms petals which attract pollinators Tepals formed by similar sepals and petals are common in monocotyledons particularly the lilioid monocots In tulips for example the first and second whorls both contain structures that look like petals These are fused at the base to form one large showy six parted structure the perianth In lilies the organs in the first whorl are separate from the second but all look similar thus all the showy parts are often called tepals Where sepals and petals can in principle be distinguished usage of the term tepal is not always consistent some authors will refer to sepals and petals where others use tepals in the same context 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 and shape EditTerms 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 Tepal shape is described in similar terms to those used for leaves see Glossary of leaf morphology Gallery EditFlowers with tepals Flowers of Magnolia alba showing tepals in various stages of development Tepals of Magnolia wieseneri A hellebore flower showing the petaloid sepals A Sternbergia lutea flower showing the two whorls of tepals A tulip flower showing the petal like tepals Tepals of Blandfordia nobilis another lilioid monocotSee also EditGlossary of plant morphology Plant reproductive morphologyReferences Edit Augustin Pyramus de Candolle 1827 Organographie vegetale ou Description raisonnee des organes des plantes pour servir de suite et de developpement a la theorie elementaire de la botanique et d introduction a la physiologie vegetale et a la physiologie vegetale et a la description des familles Paris Deterville p 503 Augustin Pyramus de Candolle 1841 Vegetable organography or An analytical description of the organs of plants Vol 2 Translated by Boughton Kingdon London Houlston amp Stoneman p 90 Stearn William Thomas 2004 Botanical Latin p b ed David amp Charles Timber Press ISBN 978 0 7153 1643 6 p 39 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 doi 10 1093 aob mcm076 PMC 2533615 PMID 17513305 Botany A Brief Introduction To Plant Biology 5th ed Thomas L Rost T Elliot Weier Wiley amp Sons 1979 ISBN 0 471 02114 8 Plant Systematics Jones Samuel McGraw Hill 1979 ISBN 0 07 032795 5 Retrieved from https en wikipedia org w index php title Tepal amp oldid 1087665383, wikipedia, wiki, book, books, library,
