In
botany
Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
, a tendril is a specialized
stem
Stem or STEM may refer to:
Plant structures
* Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
* Stipe (botany), a stalk to support some other structure
* Stipe (mycology), the stem of a mushro ...
,
leaf
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...
or
petiole with a threadlike shape used by
climbing plants
A vine (Latin ''vīnea'' "grapevine", "vineyard", from ''vīnum'' "wine") is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas or runners. The word ''vine'' can also refer to such stems or runners themselve ...
for support and attachment, as well as cellular invasion by parasitic plants such as ''
Cuscuta
''Cuscuta'' (), commonly known as dodder or amarbel, is a genus of over 201 species of yellow, orange, or red (rarely green) parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, it now is accepted as belonging in the ...
''. There are many plants that have tendrils; including sweet peas, passionflower, grapes and
Chilean glory-flower
''Eccremocarpus scaber'', the Chilean glory-flower or Chilean glory creeper, is a species of perennial plant in the Bignoniaceae family. It is found in Chile.
Description
Chilean glory creepers are a many branched perennial vine or climbing s ...
. Tendrils respond to touch and to chemical factors by curling, twining, or adhering to suitable structures or hosts.
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
Nutation refers to the bending movements of stems, roots, leaves and other plant organs caused by differences in growth in different parts of the organ. Circumnutation refers specifically to the circular movements often exhibited by the tips of gr ...
to describe the motion of growing stems and tendrils seeking supports. Darwin also observed the phenomenon now known as
tendril perversion
Tendril perversion is a geometric phenomenon sometimes observed in helical structures in which the direction of the helix transitions between left-handed and right-handed. Such a reversal of chirality is commonly seen in helical plant tendril ...
, in which tendrils adopt the shape of two sections of counter-twisted helices with a transition in the middle.
Biology of tendrils
In the
garden pea
The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds and d ...
, it is only the terminal leaflets that are modified to become tendrils. In other plants such as the yellow vetch (''
Lathyrus aphaca
''Lathyrus aphaca'', known as the yellow pea or yellow vetchling, is an annual species in the family Fabaceae with yellow flowers and solitary, pea-like fruits. It originated in the Middle East and has spread throughout Europe and beyond as a ...
''), the whole leaf is modified to become tendrils while the
stipule
In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...
s become enlarged and carry out
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
. Still others use the
rachis
In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft".
In zoology and microbiology
In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...
of a compound leaf as a tendril, such as members of the genus ''
Clematis
''Clematis'' is a genus of about 300 species within the buttercup family, Ranunculaceae. Their garden hybrids have been popular among gardeners, beginning with ''Clematis'' × ''jackmanii'', a garden standby since 1862; more hybrid cultivars ...
''.
![Tendril of climbing plant](https://upload.wikimedia.org/wikipedia/commons/d/da/Tendril_of_climbing_plant.jpg)
The specialised pitcher traps of ''
Nepenthes
''Nepenthes'' () is a genus of carnivorous plants, also known as tropical pitcher plants, or monkey cups, in the monotypic family Nepenthaceae. The genus includes about 170 species, and numerous natural and many cultivated hybrids. They are mos ...
'' 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.
Tendrils of ''
Cuscuta
''Cuscuta'' (), commonly known as dodder or amarbel, is a genus of over 201 species of yellow, orange, or red (rarely green) parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, it now is accepted as belonging in the ...
'', 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
Canopy may refer to:
Plants
* Canopy (biology), aboveground portion of plant community or crop (including forests)
* Canopy (grape), aboveground portion of grapes
Religion and ceremonies
* Baldachin or canopy of state, typically placed over an a ...
in order to receive more sunlight resources and increase the diversification in flowering plants. Tendril is a plant organ that is derived from various morphological structures such as stems, leaves and inflorescences. Even though climbing habits are involved in the
angiosperms
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
,
gymnosperm
The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, ''Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, Î³Ï…Î¼Î½ÏŒÏ ...
s, and
fern
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except t ...
, tendrils are often shown in angiosperms and little in fern. Based on their molecular basis of tendril development, studies showed that tendrils helical growth performance is not correlated with ontogenetic origin, instead, there are multiple ontogenetic origins. 17 types tendrils have been identified by their ontogenetic origins and growth pattern, and each type of tendrils can be involved more than once within angiosperms. Common fruits and vegetables that have of tendrils includes watermelon (
Citrullus lanatus
Watermelon (''Citrullus lanatus'') is a flowering plant species of the Cucurbitaceae family and the name of its edible fruit. A scrambling and trailing vine-like plant, it is a highly cultivated fruit worldwide, with more than 1,000 varieti ...
)'s derived from modified stem,
pea
The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds and d ...
(Pisum sativum)'s derived from modified terminal leaflets and
common grape vine (Vitis vinifera)'s is modified from whole inflorescence.
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.
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). 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.
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.
It is important to note that the process of circumnutation in plants is not unique to tendril plants, as almost all plant species show circumnutation behaviors.
Contact Coiling
Thigmotropism
Thigmotropism is a directional growth movement which occurs as a mechanosensory response to a touch stimulus. Thigmotropism is typically found in twining plants and tendrils, however plant biologists have also found thigmotropic responses in flowe ...
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. The primary touch signal induces a signaling cascade of other phytohormones, most notably
gamma-Aminobutyric acid (GABA) and
Jasmonate
Jasmonate (JA) and its derivatives are lipid-based plant hormones that regulate a wide range of processes in plants, ranging from growth and photosynthesis to reproductive development. In particular, JAs are critical for plant defense against herb ...
(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. This cascade can activate
Plasma membrane H+-ATPase
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood plas ...
, 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
Inside a plant, the apoplast can mean the space outside of cell membranes, where material can diffuse freely; that is, the extracellular spaces.
''Apoplast '' can also refer especially to the continuum of cell walls of adjacent cells; fluid and ma ...
, 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. This contractile movement is also influenced by gelatinous fibers, which contract and
lignify in response to the thigmotropic signal cascade.
Self-discrimination
Although tendrils twine around hosts based on
touch perception, plants have a form of self-discrimination
and avoid twining around themselves or neighboring plants of the same speciesdemonstrating
chemotropism
Chemotropism is defined as the growth of organisms navigated by chemical stimulus from outside of the organism. It has been observed in bacteria, plants and fungi. A chemical gradient can influence the growth of the organism in a positive or negat ...
based on
chemoreception
A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance (endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorecept ...
.
Once a tendril comes in contact with a neighboring
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.
Studies confirming this pathway have been performed on the climbing plant ''
Cayratia japonica
''Causonis japonica'' (also known by its synonym ''Cayratia japonica'' and common names bushkiller, yabu garashi and Japanese cayratia herb) is the type species of vine plant in its genus and is native to Tropical and Subtropical Asia, Australia ...
''. 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
Oxalate (IUPAC: ethanedioate) is an anion with the formula C2O42−. This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (Na2C2O4), and several esters such as dimethyl o ...
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.
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.
Gallery
Image:Nep raf211.jpg, ''Nepenthes rafflesiana
''Nepenthes rafflesiana'' (; after Stamford Raffles), or Raffles' pitcher-plant,Phillipps, A. & A. Lamb 1996. ''Pitcher-Plants of Borneo''. Natural History Publications (Borneo), Kota Kinabalu. is a species of tropical pitcher plant. It has a ver ...
'' upper pitcher with coiled tendril.
File:Virginiacreepertendril.jpg, Virginia Creeper vine beginning tendril
File:Kurgiväät.jpg, Cucumber
Cucumber (''Cucumis sativus'') is a widely-cultivated Vine#Horticultural climbing plants, creeping vine plant in the Cucurbitaceae family that bears usually cylindrical Fruit, fruits, which are used as culinary vegetables. tendril
File:NRCSHI07025 - Hawaii (716084)(NRCS Photo Gallery).jpg, Squash vine coiled tendril
References
External links
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Plant morphology