What does chemotropism mean?
Chemotropism is the growth or orientation of an organism, or part of an organism, in response to a chemical stimulus in its environment. The term applies chiefly to plants and fungi, whose immobile nature means they must grow toward beneficial substances rather than move toward them. When growth is directed toward the chemical source, it is described as positive chemotropism; when directed away from it, negative chemotropism. Familiar examples include plant roots that curve toward pockets of water and nutrients in the soil, and pollen tubes that navigate down the flower's style by following chemical cues released by the ovule. Fungal hyphae likewise use chemotropism to locate food sources. Closely related to phototropism (growth toward light) and geotropism (growth in response to gravity), chemotropism belongs to a family of directional growth responses that reveal how even rooted organisms actively sense and respond to their surroundings.
nounThe growth or movement of a plant or other organism in response to a chemical stimulus, either toward it (positive chemotropism) or away from it (negative chemotropism). It is most commonly observed in roots growing toward nutrients and in pollen tubes growing toward ovules.
- Growth of an organism, especially a plant, in a direction determined by a chemical stimulus.
"The pollen tube's growth down the style is guided by chemotropism toward chemical signals released by the ovule."
"Roots exhibit chemotropism, curving toward patches of soil rich in minerals."
"Fungal hyphae display chemotropism as they grow along gradients of nutrients released by their substrate."
Rarely pluralized; usually treated as an uncountable mass noun referring to the phenomenon generally.
"Different species of fungi rely on distinct chemotropisms to locate suitable hosts."
Every root tip you've ever grown was navigating blind — steering through soil by sniffing out chemical trails, one of nature's oldest GPS systems.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of chemotropism
Chemotropism combines 'chemo-', from Greek 'khēmeia' or 'khumeia' relating to chemistry, with '-tropism', from Greek 'tropos' meaning 'turn'. It entered scientific English in the late nineteenth century alongside related terms such as phototropism and heliotropism, as biologists began systematically describing directional growth responses in plants. The '-tropism' suffix remains productive in scientific terminology today, appearing in words like thermotropism and thigmotropism.
Related word forms
How chemotropism is actually used
A technical term used chiefly in botany, mycology, and developmental biology; rarely encountered outside scientific writing. The terms 'positive' and 'negative' specify whether growth is toward or away from the chemical source.
Easily confused with chemotropism
Chemotaxis is the directed movement of a whole motile cell or organism toward a chemical stimulus, whereas chemotropism is the directed growth of an organism or its parts in response to chemicals.
Chemosynthesis is the production of organic compounds using energy from chemical reactions, not a directional growth response to chemicals.