Editing Tendril

{{Short description|Specialisation of plant parts used to climb or bind}}
{{Redirect|Tendrils|the band|Tendrils (band)}}
[[Image:Vine.jpg|thumb|upright|A curling tendril]]

In [[botany]], a '''tendril''' is a specialized [[Plant stem|stem]], [[leaf]] or [[Petiole (botany)|petiole]] with a thread-like shape used by [[climbing plant]]s for support and attachment, as well as cellular invasion by parasitic plants such as ''[[Cuscuta]]''.<ref>{{Cite web|title=Plants: A Different Perspective|url=http://content.yudu.com/Library/A1og25/PlantsADifferentPers/resources/73.htm|url-status=live|archive-url=https://web.archive.org/web/20170217195618/http://content.yudu.com/Library/A1og25/PlantsADifferentPers/resources/73.htm|archive-date=2017-02-17|access-date=2018-01-09|website=content.yudu.com|language=en}}</ref> There are many plants that have tendrils; including sweet peas, passionflower, grapes and the [[Chilean glory-flower]].<ref>{{Cite web |title=How Plants Climb - Climbing Plants & Vines {{!}} Gardener's Supply |url=https://www.gardeners.com/how-to/how-plants-climb/5373.html |access-date=2022-04-27 |website=www.gardeners.com |language=en-US}}</ref> Tendrils respond to touch and to chemical factors by curling, twining, or adhering to suitable structures or hosts. Tendrils vary greatly in size from a few centimeters up to 27 inches (69 centimeters) for ''[[Nepenthes harryana]]''.<ref>{{cite book |last=Kurata |first=Shigeo |date=1976 |title=Nepenthes of Mount Kinabalu |location=Kota Kinabalu, Malaysia |publisher=National Parks Trust |page=47 }}</ref> The chestnut vine (''[[Tetrastigma voinierianum]]'') can have tendrils up to 20.5 inches (52 centimeters) in length.  Normally there is only one simple or branched tendril at each node (see [[plant stem]]), but the aardvark cucumber (''[[Cucumis humifructus]]'') can have as many as eight.<ref>{{cite book |last=Kilbride Jr. |first=Joseph H. |date=1993 |title=Biosystematic Monograph of the Genus Cucumis |location=Bonne, No. Carolina |publisher=Parkway Publishers |page=77 }}</ref>

== History ==
The earliest and most comprehensive study of tendrils was [[Charles Darwin]]'s monograph ''On the Movements and Habits of Climbing Plants'', which was originally published in 1865. This work also coined the term [[circumnutation]] to describe the motion of growing stems and tendrils seeking supports. Darwin also observed the phenomenon now known as [[tendril perversion]], in which tendrils adopt the shape of two sections of counter-twisted helices with a transition in the middle.<ref>Charles Darwin, "On the movements and habits of climbing plants", ''Journal of the Linnean Society'', 1866.</ref>

== Biology of tendrils ==
In the [[garden pea]], it is only the terminal leaflets that are modified to become tendrils. In other plants such as the yellow vetch (''[[Lathyrus aphaca]]''), the whole leaf is modified to become tendrils while the [[stipule]]s become enlarged and carry out [[photosynthesis]]. Still others use the [[rachis]] of a compound leaf as a tendril, such as members of the genus ''[[Clematis]]''.
[[File:Tendril of climbing plant.jpg|thumb|Tendril of a common climbing plant]]
The specialised pitcher traps of ''[[Nepenthes]]'' plants form on the end of tendrils. The tendrils of aerial pitchers are usually coiled in the middle. If the tendril comes into contact with an object for long enough it will usually curl around it, forming a strong anchor point for the pitcher. In this way, the tendrils help to support the growing stem of the plant.<ref>Clarke, C.M. 1997. ''Nepenthes of Borneo''. Natural History Publications, Kota Kinabalu.</ref> Tendrils of ''[[Cuscuta]]'', a parasitic plant, are guided by airborne chemicals, and only twine around suitable hosts.

=== Evolution and species ===
Climbing habits in plants support themselves to reach the [[Canopy (biology)|canopy]] in order to receive more sunlight resources and increase the diversification in flowering plants.<ref>{{Cite journal|last=Gianoli|first=Ernesto|date=2004-10-07|title=Evolution of a climbing habit promotes diversification in flowering plants|journal=Proceedings of the Royal Society of London. Series B: Biological Sciences|volume=271|issue=1552|pages=2011–2015|doi=10.1098/rspb.2004.2827|pmc=1691831|pmid=15451690}}</ref> Tendrils are a plant organ that is derived from various morphological structures such as stems, leaves and inflorescences. Even though climbing habits are involved in the [[Angiosperm Phylogeny Group|angiosperms]], [[gymnosperm]]s, and [[fern]]s,<ref>{{Citation|last1=Isnard|first1=Sandrine|title=The evolution of angiosperm lianescence: a perspective from xylem structure-function|date=2015|url=https://onlinelibrary.wiley.com/doi/abs/10.1002/9781118392409.ch17|work=Ecology of Lianas|pages=221–238|publisher=John Wiley & Sons, Ltd|language=en|doi=10.1002/9781118392409.ch17|isbn=978-1-118-39240-9|access-date=2021-06-05|last2=Feild|first2=Taylor S.|url-access=subscription}}</ref> tendrils are often shown in angiosperms and little in ferns. Based on their molecular basis of tendril development, studies showed that tendrils' helical growth performance is not correlated with ontogenetic origin,<ref>{{Cite journal|last1=Sousa-Baena|first1=Mariane S.|last2=Lohmann|first2=Lúcia G.|last3=Hernandes-Lopes|first3=José|last4=Sinha|first4=Neelima R.|date=2018|title=The molecular control of tendril development in angiosperms|journal=New Phytologist|language=en|volume=218|issue=3|pages=944–958|doi=10.1111/nph.15073|pmid=29520789|s2cid=4860319 |issn=1469-8137|doi-access=free|bibcode=2018NewPh.218..944S }}</ref> instead, there are multiple ontogenetic origins. 17 types of tendrils have been identified by their ontogenetic origins and growth pattern, and each type of tendril can be involved more than once within angiosperms. Common fruits and vegetables that have tendrils includes [[watermelon]] (''Citrullus lanatus'')'s derived from modified stem, [[pea]] (''Pisum sativum'')'s derived from modified terminal leaflets and [[Vitis vinifera|common grape vine]] (''Vitis vinifera'')'s is modified from whole inflorescence.<ref>{{Cite journal|last1=Sousa-Baena|first1=Mariane S.|last2=Sinha|first2=Neelima R.|last3=Hernandes-Lopes|first3=José|last4=Lohmann|first4=Lúcia G.|date=2018|title=Convergent Evolution and the Diverse Ontogenetic Origins of Tendrils in Angiosperms|journal=Frontiers in Plant Science|language=English|volume=9|page=403|doi=10.3389/fpls.2018.00403|pmid=29666627|pmc=5891604|issn=1664-462X|doi-access=free}}</ref>

== Coiling mechanism ==
=== Circumnutation ===
The mechanism of tendril coiling begins with circumnutation of the tendril in which it is moving and growing in a circular oscillatory pattern around its axis.<ref name=":0">{{Cite journal|last=Kiss|first=John Z.|date=2009|title=Plants circling in outer space|journal=New Phytologist|language=en|volume=182|issue=3|pages=555–557|doi=10.1111/j.1469-8137.2009.02817.x|pmid=19422543|issn=1469-8137|doi-access=free|bibcode=2009NewPh.182..555K }}</ref> Circumnutation is often defined as the first main movement of the tendril, and it serves the purpose of increasing the chance that the plant will come in contact with a support system (physical structure for the tendril to coil around).<ref>{{Cite journal|last1=Malabarba|first1=Jaiana|last2=Reichelt|first2=Michael|last3=Pasquali|first3=Giancarlo|last4=Mithöfer|first4=Axel|date=2019-03-01|title=Tendril Coiling in Grapevine: Jasmonates and a New Role for GABA?|url=https://doi.org/10.1007/s00344-018-9807-x|journal=Journal of Plant Growth Regulation|language=en|volume=38|issue=1|pages=39–45|doi=10.1007/s00344-018-9807-x|s2cid=13792885|issn=1435-8107|hdl=21.11116/0000-0001-1BB3-7|hdl-access=free}}</ref> In a 2019 study done by Guerra et al., it was shown that without a support stimulus, in this case a stake in the ground, the tendrils will circumnutate towards a light stimulus. After many attempts to reach a support structure, the tendril will eventually fall to the ground.<ref name=":1">{{Cite journal|last1=Guerra|first1=Silvia|last2=Peressotti|first2=Alessandro|last3=Peressotti|first3=Francesca|last4=Bulgheroni|first4=Maria|last5=Baccinelli|first5=Walter|last6=D’Amico|first6=Enrico|last7=Gómez|first7=Alejandra|last8=Massaccesi|first8=Stefano|last9=Ceccarini|first9=Francesco|last10=Castiello|first10=Umberto|date=2019-11-12|title=Flexible control of movement in plants|journal=Scientific Reports|language=en|volume=9|issue=1|pages=16570|doi=10.1038/s41598-019-53118-0|pmid=31719580|pmc=6851115|bibcode=2019NatSR...916570G|issn=2045-2322}}</ref> However, it was found that when a support stimulus is present, the tendril’s circumnutation oscillation occurs in the direction of the support stimulus. Therefore, it was concluded that tendrils are able to change the direction of their circumnutation based on the presence of a support stimulus.<ref name=":1" /> The process of circumnutation in plants is not unique to tendril plants, as almost all plant species show circumnutation behaviors.<ref name=":0" />

=== Contact coiling ===
[[Thigmotropism]] is the basis of the input signal in the tendril coiling mechanism. For example, pea tendrils have highly sensitive cells in the surfaces of cell walls that are exposed. These sensitized cells are the ones that initiate the thigmotropic signal, typically as a calcium wave.<ref>{{Cite journal|last1=Jaffe|first1=M. J.|last2=Leopold|first2=A. C.|last3=Staples|first3=R. C.|date=2002-03-01|title=Thigmo responses in plants and fungi|journal=American Journal of Botany|language=en|volume=89|issue=3|pages=375–382|doi=10.3732/ajb.89.3.375|pmid=21665632|issn=0002-9122|doi-access=free}}</ref> The primary touch signal induces a signaling cascade of other phytohormones, most notably [[gamma-Aminobutyric acid]] (GABA) and [[Jasmonate]] (JA). In grapevine tendrils, it recently has been shown that GABA can independently promote tendril coiling. It has also been shown that jasmonate phytohormones serve as a hormonal signal to initiate tendril coiling.<ref>{{Cite journal|last1=Malabarba|first1=Jaiana|last2=Reichelt|first2=Michael|last3=Pasquali|first3=Giancarlo|last4=Mithöfer|first4=Axel|date=March 2019|title=Tendril Coiling in Grapevine: Jasmonates and a New Role for GABA?|url=http://link.springer.com/10.1007/s00344-018-9807-x|journal=Journal of Plant Growth Regulation|language=en|volume=38|issue=1|pages=39–45|doi=10.1007/s00344-018-9807-x|s2cid=13792885|issn=0721-7595|hdl=21.11116/0000-0001-1BB3-7|hdl-access=free}}</ref> This cascade can activate [[plasma membrane H+-ATPase]], which also plays a role in the contact coiling mechanism as a proton pump. This pump activity establishes an electrochemical of H+ ions from inside the cell to the [[apoplast]], which in turn creates an osmotic gradient. This leads to loss of turgor pressure; the differences in cell size due to the loss of turgor pressure in some cells creates the coiling response.<ref>{{Cite journal|last1=Jaffe|first1=M. J.|last2=Galston|first2=A. W.|date=1968-04-01|title=Physiological Studies on Pea Tendrils. V. Membrane Changes and Water Movement Associated with Contact Coiling|journal=Plant Physiology|language=en|volume=43|issue=4|pages=537–542|doi=10.1104/pp.43.4.537|issn=0032-0889|pmc=1086884|pmid=16656803}}</ref> This contractile movement is also influenced by gelatinous fibers, which contract and [[Lignin|lignify]] in response to the thigmotropic signal cascade.<ref>{{Cite journal|last1=Bowling|first1=Andrew J.|last2=Vaughn|first2=Kevin C.|date=April 2009|title=Gelatinous fibers are widespread in coiling tendrils and twining vines|journal=American Journal of Botany|language=en|volume=96|issue=4|pages=719–727|doi=10.3732/ajb.0800373|pmid=21628227|doi-access=free}}</ref>

=== Self-discrimination ===
Although tendrils twine around hosts based on [[Thigmotropism|touch perception]], plants have a form of self-discrimination<ref name=":2">{{cite journal |last1=Fukano |first1=Yuya |last2=Yamawo |first2=Akira |title=Self-discrimination in the tendrils of the vine is mediated by physiological connection |journal=Proceedings of the Royal Society B: Biological Sciences |date=26 August 2015 |volume=282 |issue=1814 |pages=20151379 |doi=10.1098/rspb.2015.1379 |pmid=26311669 |pmc=4571702}}</ref> and avoid twining around themselves or neighboring plants of the same species{{snd}}demonstrating [[chemotropism]] based on [[chemoreception]].<ref name=":3">{{cite journal |last1=Fukano |first1=Yuya |title=Vine tendrils use contact chemoreception to avoid conspecific leaves |journal=Proceedings of the Royal Society B: Biological Sciences |date=15 March 2017 |volume=284 |issue=1850 |pages=20162650 |doi=10.1098/rspb.2016.2650 |pmid=28250182 |pmc=5360923}}</ref> Once a tendril comes in contact with a neighboring [[Conspecific|conspecific plant]] (of the same species) signaling molecules released by the host plant bind to chemoreceptors on the climbing plant’s tendrils. This generates a signal that prevents the thigmotropic pathway and therefore prevents the tendril from coiling around that host.<ref name=":2" />

Studies confirming this pathway have been performed on the climbing plant ''[[Cayratia japonica]]''. Research demonstrated that when two ''C. japonica'' plants were placed in physical contact, the tendrils would not coil around the conspecific plant. Researchers tested this interaction by isolating [[oxalate]] crystals from the leaves of a ''C. japonica'' plant and coating a stick with the oxalate crystals. The tendrils of ''C. japonica'' plants that came in physical contact with the oxalate-coated stick would not coil, confirming that climbing plants use chemoreception for self-discrimination.<ref name=":3" />

Self-discrimination may confer an evolutionary advantage for climbing plants to avoid coiling around conspecific plants. This is because neighboring climbing plants do not provide as stable of structures to coil around when compared to more rigid nearby plants. Furthermore, by being able to recognize and avoid coiling around conspecific plants, the plants reduce their proximity to competition, allowing them to have access to more resources and therefore better growth.<ref name=":2" />

==Gallery==
<gallery widths="180" heights="180" perrow="4">
File:Nep raf211.jpg|''[[Nepenthes rafflesiana]]'' upper pitcher with coiled tendril.
File:Virginiacreepertendril.jpg|[[Virginia creeper]] vine beginning tendril
File:Kurgiväät.jpg|[[Cucumber]] tendril
File:NRCSHI07025 - Hawaii (716084)(NRCS Photo Gallery).jpg|Squash vine coiled tendril
</gallery>

==References==
{{Reflist}}

==External links==
*{{Commons category-inline|Tendrils}}

{{Authority control}}

[[Category:Leaf morphology]]