The hyponastic response is an upward bending of

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

or other

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

parts, resulting from accelerated growth of the lower side of the petiole in comparison to its upper part. This can be observed in many terrestrial plants and is linked to the

plant hormone Plant hormone (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pa ...

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

. The plant’s root senses the water excess and produces 1-Aminocyclopropane-1-carboxylic acid which then is converted into ethylene, regulating this process.(Manual interactivo de fisiología vegetal;Facultad de Agronomía;Montevideo) Submerged plants often show the hyponastic response, where the upward bending of the leaves and the elongation of the petioles might help the plant to restore normal gas exchange with the atmosphere. Plants that are exposed to elevated ethylene levels in experimental set-ups also show the hyponastic response.

References

{{DEFAULTSORT:Hyponastic Response Plant physiology Botany