Editing Sepal (section)

==Description==

The term ''[[tepal]]'' is usually applied when the parts of the [[perianth]] are difficult to distinguish,<ref name="Beentje2010p119">{{Harvnb|Beentje|2010|p=119}}</ref> e.g. the petals and sepals share the same color or the petals are absent and the sepals are colorful. When the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in [[petaloid monocots]], orders of monocots with brightly colored tepals. Since they include [[Liliales]], an alternative name is lilioid monocots. Examples of plants in which the term tepal is appropriate include genera such as ''[[Aloe]]'' and ''[[Tulipa]]''. In contrast, genera such as ''[[Rose|Rosa]]'' and ''[[Phaseolus]]'' have well-distinguished sepals and petals. {{citation needed|date=April 2014}}

The number of sepals in a flower is its [[merosity]].  Flower merosity is indicative of a plant's classification. The merosity of a [[eudicots|eudicot]] flower is typically four or five.  The merosity of a [[monocotyledon|monocot]] or [[Basal angiosperms|palaeodicot]] flower is three, or a multiple of three.

The development and form of the sepals vary considerably among [[flowering plant]]s.<ref>Sattler, R. 1973. ''Organogenesis of Flowers. A Photographic Text-Atlas''. University of Toronto Press. {{ISBN|0-8020-1864-5}}.</ref> They may be free (polysepalous) or fused together (gamosepalous).{{sfn|Beentje|2010|pp=51 & 91}} Often, the sepals are much reduced, appearing somewhat [[Awn (botany)|awn]]-like, or as scales, teeth, or ridges. Most often such structures protrude until the fruit is mature and falls off.

Examples of flowers with much-reduced perianths are found among the [[Poaceae|grasses]].

In some flowers, the sepals are fused towards the base, forming a ''calyx tube'' (as in the family [[Lythraceae]],<ref>{{Cite web |last=Carr |first=Gerald |title=''Lythraceae'' |url=http://www.botany.hawaii.edu/FACULTY/CARR/lythr.htm |url-status=dead |archive-url=https://web.archive.org/web/20081205132651/http://www.botany.hawaii.edu/faculty/carr/lythr.htm |archive-date=5 December 2008 |access-date=20 December 2008 |publisher=University of Hawaii}}</ref> and [[Fabaceae]]). In other flowers (e.g., Rosaceae, Myrtaceae), a [[hypanthium]] includes the bases of sepals, petals, and the attachment points of the [[stamen]]s.

Mechanical cues may be responsible for sepal growth and there is a strong evidence suggesting that microtubules are present and determine the tensile strength and direction of growth at a molecular level.<ref>{{Cite journal |last1=Hervieux |first1=Nathan |last2=Dumond |first2=Mathilde |last3=Sapala |first3=Aleksandra |last4=Routier-Kierzkowska |first4=Anne-Lise |last5=Kierzkowski |first5=Daniel |last6=Roeder |first6=Adrienne H.K. |last7=Smith |first7=Richard S. |last8=Boudaoud |first8=Arezki |last9=Hamant |first9=Olivier |date=April 2016 |title=A Mechanical Feedback Restricts Sepal Growth and Shape in Arabidopsis |journal=Current Biology |language=en |volume=26 |issue=8 |pages=1019–1028 |doi=10.1016/j.cub.2016.03.004 |pmid=27151660 |doi-access=free|bibcode=2016CBio...26.1019H |hdl=11858/00-001M-0000-002B-1620-2 |hdl-access=free }}</ref>