Skip to main content
Select Source:

geotropism

geotropism (gravitropism) The growth of plant organs in response to gravity. A main root is positively geotropic and a main stem negatively geotropic, growing downwards and upwards respectively, irrespective of the positions in which they are placed. For example, if a stem is placed in a horizontal position it will still grow upwards. It is thought that mobile membrane-bound clusters of starch grains (amyloplasts) sink to the bottom of a plant cell, under the influence of gravity, and somehow create a physiological asymmetry within the cell. This results in differential growth of the upper and lower sides of the cell, and hence upward or downward curvature of the organ concerned, depending on whether it is a root or a shoot. The biochemical mechanisms of this differential growth remain largely unknown, although auxins are required for geotropism in shoots, and also possibly in roots, and there is evidence that calcium ions play a role too. See tropism.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"geotropism." A Dictionary of Biology. . Encyclopedia.com. 23 Jun. 2017 <http://www.encyclopedia.com>.

"geotropism." A Dictionary of Biology. . Encyclopedia.com. (June 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/geotropism-1

"geotropism." A Dictionary of Biology. . Retrieved June 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/geotropism-1

geotropism

ge·ot·ro·pism / jēˈätrəˌpizəm/ • n. Bot. the growth of the parts of plants with respect to the force of gravity. The upward growth of plant shoots is an instance of negative geotropism; the downward growth of roots is positive geotropism. DERIVATIVES: ge·o·trop·ic / ˌjēəˈträpik; -ˈtrō-/ adj.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"geotropism." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 23 Jun. 2017 <http://www.encyclopedia.com>.

"geotropism." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (June 23, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/geotropism

"geotropism." The Oxford Pocket Dictionary of Current English. . Retrieved June 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/geotropism

geotropism

geotropism A directional movement of a plant in response to the stimulus of gravity. Primary tap roots show positive geotropism; vertical primary shoots show negative geotropism; horizontal stems and leaves are diageotropic (see diageotropism); and branches and secondary roots at oblique angles are plagiogeotropic.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"geotropism." A Dictionary of Ecology. . Encyclopedia.com. 23 Jun. 2017 <http://www.encyclopedia.com>.

"geotropism." A Dictionary of Ecology. . Encyclopedia.com. (June 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/geotropism

"geotropism." A Dictionary of Ecology. . Retrieved June 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/geotropism

geotropism

geotropism A directional movement of a plant in response to the stimulus of gravity. Primary tap roots show positive geotropism; vertical primary shoots show negative geotropism; horizontal stems and leaves are diageotropic (see DIAGEOTROPISM); and branches and secondary roots at oblique angles are plagiogeotropic.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"geotropism." A Dictionary of Plant Sciences. . Encyclopedia.com. 23 Jun. 2017 <http://www.encyclopedia.com>.

"geotropism." A Dictionary of Plant Sciences. . Encyclopedia.com. (June 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/geotropism-0

"geotropism." A Dictionary of Plant Sciences. . Retrieved June 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/geotropism-0