A
chemotype (sometimes
chemovar) is a chemically distinct entity in a
plant or
microorganism, with differences in the composition of the
secondary metabolites. Minor
genetic and
epigenetic changes with little or no effect on morphology or anatomy may produce large changes in the chemical
phenotype. Chemotypes are often defined by the most abundant chemical produced by that individual and the concept has been useful in work done by chemical ecologists and natural product chemists. With respect to plant biology, the term "chemotype" was first coined by Dr. Rolf Santesson and his son Johan in 1968, defined as, "...chemically characterized parts of a population of morphologically indistinguishable individuals."