Editing Tepal

{{Short description|One of the outer parts of a flower}}
[[File:Mature flower diagram.svg|thumb|upright=1.4|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 one of the outer parts of a [[flower]] (collectively the [[perianth]]). The term is used when these parts cannot easily be classified as either [[sepal]]s or [[petal]]s. 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 (botany)|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".<ref>{{cite book|url=https://www.biodiversitylibrary.org/item/60660#page/527/mode/1up|title=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|author=Augustin Pyramus de Candolle |year=1827|publisher=Deterville|location=Paris|page=503}}</ref><ref>{{cite book|author=Augustin Pyramus de Candolle|year=1841|title=Vegetable organography; or, An analytical description of the organs of plants|translator=Boughton Kingdon|volume=2|page=90|url=https://www.biodiversitylibrary.org/item/70328#page/104/mode/1up|publisher=Houlston & Stoneman|location=London}}</ref> (De Candolle used the term ''perigonium'' or ''perigone'' for the tepals collectively; today, this term is used as a synonym for ''perianth''.)<ref name=Stea04>{{Cite book |last=Stearn |first=William Thomas |year=2004 |title=Botanical Latin |edition=p/b |publisher=David & Charles/Timber Press |isbn=978-0-7153-1643-6 }} p. 39.</ref>

== Origin ==
[[Image:Zanlophator1a.UME.jpg|right|200px|thumb|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 plant]]s. For example, ''[[Amborella]]'', which is thought to have separated earliest in the evolution of flowering plants,<ref>{{Cite journal | last1 = Ronse De Craene | first1 = L. P. | title = Are Petals Sterile Stamens or Bracts? The Origin and Evolution of Petals in the Core Eudicots | doi = 10.1093/aob/mcm076 | journal = Annals of Botany | volume = 100 | issue = 3 | pages = 621–630 | year = 2007 | pmid =  17513305| pmc =2533615 }}</ref> 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, and is specialised for protection of the flower bud as it develops, while the inner whorl forms petals, which attract [[pollinator]]s.

Tepals formed by similar sepals and petals are common in [[monocotyledon]]s, particularly the "[[lilioid monocot]]s". In [[tulip]]s, 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 [[Lilium|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 [[hellebore]]s. 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 ==
<gallery  widths="200px" heights="180px"  caption="Flowers with tepals">
File:Magnolia-x-alba-bud-comparison.jpg|Flowers of [[Magnolia × alba|''Magnolia'' × ''alba'']] showing tepals in various stages of development
File:Magnolia wieseneri.jpg|Tepals of [[Magnolia × wieseneri|''Magnolia'' ×&nbsp;''wieseneri'']]
File:2006-12-18Helleborus_niger19.jpg|A [[hellebore]] flower showing the petaloid sepals
File:Sternbergia lutea showing the different parts of the flower.JPG|A ''[[Sternbergia lutea]]'' flower showing the two whorls of tepals
File:Tulip_-_floriade_canberra02.jpg|A tulip flower showing the petal-like tepals
File:Blandfordia_nobilis_Berowra_Valley.JPG|Tepals of ''[[Blandfordia nobilis]]'', another [[lilioid monocot]]
File:Juncus.squarrosus3.-.lindsey.jpg|6 tepals (3 inner, 3 outer) of the rush ''[[Juncus squarrosus]]''
</gallery>

==See also==
* [[Glossary of plant morphology]]
* [[Plant reproductive morphology]]

==References==
{{Reflist}}
*''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}}.

{{botany}}

[[Category:Plant morphology]]