providing a protective function within the plant, they tend to be concentrated in young, tender leaves, shoots, and roots, or in reproductive structures (e.g., flowers and seeds). For example, livestock poisoning episodes have shown that there is often a bimodal distribution of toxic hazard with very young plants and plants at the reproductive stage being toxic, whereas at other growth stages no problems occur. (For a more complete discussion, see Appendix C and resources listed.) Frequently, compounds are continuously biosynthesized in a particular part of the plant, such as mature leaves where photosynthesis is at a maximum, but then they are transported and accumulated in other organs where the protective function conferred by such substances is required (Harborne, 1993).

Although it is possible for plants to contain completely different chemical entities in different parts, it is generally more likely that they will contain the same compounds or compounds that have undergone relatively minor structural transformations. The situation with respect to structural types of constituents is often under a state of continuous flux in response to environmental conditions and ecological factors. It is therefore appropriate to assume, in the absence of other information to the contrary, that a plant part marketed as a dietary supplement ingredient contains toxins that are found in other parts of the plant. That is, if a toxic chemical is present in one part of the plant, it will generally be present in the other parts of the plants, even if at lower concentrations. Indeed, concentrations of toxins