biology Biology is the scientific study of life and living organisms. It is a broad natural science that encompasses a wide range of fields and unifying principles that explain the structure, function, growth, History of life, origin, evolution, and ...

, nastic movements are non-directional responses to

stimuli A stimulus is something that causes a physiological response. It may refer to: *Stimulation **Stimulus (physiology), something external that influences an activity **Stimulus (psychology), a concept in behaviorism and perception *Stimulus (economi ...

(e.g.

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

, light

irradiance In radiometry, irradiance is the radiant flux ''received'' by a ''surface'' per unit area. The SI unit of irradiance is the watt per square metre (symbol W⋅m−2 or W/m2). The CGS unit erg per square centimetre per second (erg⋅cm−2⋅s−1) ...

) that occur more rapidly than

tropism In biology, a tropism is a phenomenon indicating the growth or turning movement of an organism, usually a plant, in response to an environmental stimulus (physiology), stimulus. In tropisms, this response is dependent on the direction of the s ...

s and are usually associated with

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s. The movement can be due to changes in

turgor Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is also called ''hydrostatic pressure'', and is defined as the pressure in a fluid measured at a certain point within itself when at equilib ...

(internal pressure within

plant cells Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capab ...

). Decrease in turgor pressure causes shrinkage, while increase in turgor pressure brings about swelling. Nastic movements differ from tropic movements in that the direction of tropic responses depends on the direction of the stimulus, whereas the direction of nastic movements is independent of the stimulus's position. The tropic movement is growth movement but nastic movement may or may not be growth movement. The rate or

frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

of these responses increases as intensity of the stimulus increases. An example of such a response is the opening and closing of

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s (photonastic response), movement of

euglena ''Euglena'' is a genus of Unicellular organism, single-celled, flagellate eukaryotes. It is the best-known and most widely studied member of the class Euglenoidea, a diverse group containing some 54 genera and at least 200 species. Species of '' ...

chlamydomonas ''Chlamydomonas'' ( ) is a genus of green algae consisting of about 150 species of unicellular organism, unicellular flagellates, found in stagnant water and on damp soil, in freshwater, seawater, and even in snow as "snow algae". ''Chlamydom ...

towards the source of light . They are named with the suffix "-nasty" and have prefixes that depend on the stimuli: * Epinasty: downward-bending from growth at the top, for example, the bending down of a heavy flower. * Hyponasty: upward bending of leaves from growth in the petiole (leaf stalk) * Photonasty: response to light *

Nyctinasty In plant biology, nyctinasty is the circadian rhythm-based nastic movement of higher plants in response to the onset of darkness, or a plant "sleeping". Nyctinastic movements are associated with diurnal light and temperature changes and con ...

: movements at night or in the dark * Chemonasty: response to chemicals or nutrients * Hydronasty: response to water *

Thermonasty In plant biology, thermonasty is a nondirectional response to temperature in plants. It is a form of nastic movement, not to be confused with thermotropism, which is a directional response in plants to temperature. A common example of this is ...

: response to temperature * Seismonasty: response to shock * Geonasty/gravinasty: response to gravity *

Thigmonasty In biology, thigmonasty or seismonasty is the nastic movement, nastic (non-directional) response of a plant or fungus to touch or vibration. Conspicuous examples of thigmonasty include many species in the Fabaceae, leguminous family (biology), su ...

/seismonasty/haptonasty: response to contact The suffix may come from Greek νάσσω = 'I press', ναστός = 'pressed', ἐπιναστια = 'the condition of being pressed upon'.

References

External links

'Daisy - 'Day's Eye or Eye of the Day'.
Physiology Articles containing video clips {{Botany-stub de:Pflanzenbewegung#Nastien und Tropismen

See also

References

External links