Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
change in the direction of growth of plant organs under the influence of chemical substances acting in one direction. Like other tropisms, chemotropism results from the uneven growth of opposite sides of an organ. Many substances that stimulate positive chemotropism in low concentrations (growth of organs in the direction of the chemical stimulus) may cause negative chemotropism in high concentrations (growth of organs in the direction opposite the stimulus). Chemotropism occurs in the growth of pollen tubules toward the ovules, in the penetration of the tissue of the host plant by the hyphae of parasitic fungi, and in the growth of roots toward particles or granules of fertilizer.