Breadth of Expected Chemical Variability. Plant metabolites exhibit wide structural variability, reflecting their wide range of functions for growth, survival, and reproduction. Plants also produce metabolites ahead of their death and to protect themselves from abiotic stress, harmful environmental pollution, and other external danger such as herbivores or for interspecies defense. Each plant produces specific chemical markers with minor phytochemical derivatives that are involved directly or indirectly in their survival. The production of all these constituents is affected by the condition of soil, cultivation, and time of harvest. While a single, ideally highly taxon-specific metabolite can be used as a reference standard for ID and DS fraud detection under specific circumstances, this approach does not capture the chemical variability of plants. This points to the contemptuous question, how natural chemical variation can be distinguished from adulteration.