Thigmotropism
Encyclopedia
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
moves or grows in response to touch or contact stimuli
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....
. The prefix thigmo- θιγμος comes from the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
for "touch". Usually thigmotropism occurs when plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
s grow around a surface
Surface
In mathematics, specifically in topology, a surface is a two-dimensional topological manifold. The most familiar examples are those that arise as the boundaries of solid objects in ordinary three-dimensional Euclidean space R3 — for example, the surface of a ball...
, such as a wall
Wall
A wall is a usually solid structure that defines and sometimes protects an area. Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into rooms, or protects or delineates a space in the open air...
, pot
Pottery
Pottery is the material from which the potteryware is made, of which major types include earthenware, stoneware and porcelain. The place where such wares are made is also called a pottery . Pottery also refers to the art or craft of the potter or the manufacture of pottery...
, or trellis
Trellis
Trellis may refer to:* Trellis Drainage System* Trellis , an architectural structure often used to support plants* Trellis , a special kind of graph, often used in coding...
. Climbing plants, such as vine
Vine
A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...
s, develop tendril
Tendril
In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape that is used by climbing plants for support, attachment and cellular invasion by parasitic plants, generally by twining around suitable hosts. They do not have a lamina or blade, but they can photosynthesize...
s that coil
Coil
A coil is a series of loops. A coiled coil is a structure in which the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...
around supporting objects. Touched cells produce auxin
Auxin
Auxins are a class of plant hormones with some morphogen-like characteristics. Auxins have a cardinal role in coordination of many growth and behavioral processes in the plant's life cycle and are essential for plant body development. Auxins and their role in plant growth were first described by...
and transport it to untouched cells. Some untouched cells will then elongate faster so cell growth
Cell growth
The term cell growth is used in the contexts of cell development and cell division . When used in the context of cell division, it refers to growth of cell populations, where one cell grows and divides to produce two "daughter cells"...
bends around the object. Some seedlings also inhibit triple response, caused by pulses of ethylene
Ethylene
Ethylene is a gaseous organic compound with the formula . It is the simplest alkene . Because it contains a carbon-carbon double bond, ethylene is classified as an unsaturated hydrocarbon. Ethylene is widely used in industry and is also a plant hormone...
which cause the stem to thicken (grow slower and stronger) and curve to start growing horizontally.
Mimosa pudica
Mimosa pudica
Mimosa pudica , is a creeping annual or perennial herb often grown for its curiosity value: the compound leaves fold inward and droop when touched or shaken, re-opening minutes later...
is well known for its rapid plant movement
Rapid plant movement
Rapid plant movement encompasses movement in plant structures occurring over a very short period of time, usually under one second. For example, the Venus Flytrap closes its trap in about 100 milliseconds. The Dogwood Bunchberry's flower opens its petals and fires pollen in less than 0.5 milliseconds...
. The leaves close up and droop when touched. However, this is not a form of tropism
Tropism
A tropism is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus. In tropisms, this response is dependent on the direction of the stimulus...
but a nastic movement, a similar phenomenon. The difference is that tropisms are influenced by the direction of their stimulus, while nastic movements are not.