Thigmonasty

[1][2] Conspicuous examples of thigmonasty include many species in the leguminous subfamily Mimosoideae, active carnivorous plants such as Dionaea and a wide range of pollination mechanisms.

For example, tendrils from a climbing plant are thigmotropic because they twine around any support they touch, responding in whichever direction the stimulus came from.

The time scales of thigmonastic responses tend to be shorter than those of thigmotropic movements because many examples of thigmonasty depend on pre-accumulated turgor or on bistable mechanisms rather than growth or cell division.

Certain dramatic examples of rapid plant movement such as the sudden drooping of Mimosa pudica or the trapping action of Dionaea or Utricularia are fast enough to observe without time lapse photography; some take less than a second.

Speed is no clear distinction however; for example the re-erection of Mimosa leaves is nastic, but typically takes some 15 to 30 minutes, rather than a second or so.

[4] In species with the fastest response time, vacuoles are believed to provide temporary, high speed storage for calcium ions.

Investigators have observed an action potential and changes in leaf turgor that accompany the reflex; they trigger the rapid elongation of individual cells.

[6] The sundews (genus Drosera) are all capable of moving their glandular tentacles toward the center of a leaf in response to a prey item landing on it.