heliotropism
nounEtymology From helio- + -tropism.
1
Biology, Botany, Natural sciences The property of some plants of turning under the influence of light; either positively (towards the light) or negatively (away from the light).
- As soon as the faintest ray of light reaches a seedling, heliotropism will guide it through any crack in the soil, or through an entangled mass of overlying vegetation; […]1880 November 6, Charles Darwin, Francis Darwin, chapter XII, in The Power of Movement in Plants, page 555:
- A field of young sunflowers will slowly rotate from east to west during the course of a sunny day, each leaf seeking out as much sunlight as possible as the sun moves across the sky through an adaptation called heliotropism.2012, Staff (University of Wisconsin-Madison), Sunflowers inspire more efficient solar power system, R&D Magazine, online
- Related terms
- heliotrope, heliotropic, paraheliotropic