The entire specimen, from roots to seeds, must often be used to distinguish between botanical species or varieties. It is possible that similar plants may have overlapping marker compounds, yet differ in other, as yet unidentified, biologically active components. There are even differences among botanicals that are of the same variety. The environment where the plant is grown can vastly affect the chemical quality of a plant. The part of the botanical from which dietary supplements are produced can contribute to diversity among products.
Manufacturers use various combinations of the leaves, stems, roots, and other plant parts.
A botanical's active components may concentrate in a specific location within the plant. Dosage formulations are also left to the manufacturer's discretion. The content and potency of botanical products may vary greatly depending upon the formulation. It is difficult to control the amount of dietary supplement delivered by a tea preparation because brewing times are likely to be dissimilar. Contamination is an issue for botanical agents.