AbstractThe contribution of roots to the biology of the whole plant is being reevaluated in the light of classical and recent findings. In addition to their role in water and nutrient uptake and in symbiotic associations, plant roots also synthesize a remarkable variety of secondary metabolites. These chemicals, many of which are used as pharmaceuticals, agrichemicals, flavors, dyes, or fragrances, may help the plant cope with biotic and abiotic stress. Root cultures are being used as experimental systems to explore both root‐specific secondary metabolites and their biological significance. They may also provide future systems for commercial production of plant specialty chemical