Life cycle, seasonal- and tissue-dependent metabolite composition, and high (E)-Ligustilide content characterize the ethnobotany of a Native American medicinal plant, Lomatium foeniculaceum.

Native Americans have historically used roots, shoots, and seeds of Lomatium species for various dietary and medicinal purposes. Lomatium foeniculaceum is a perennial parsley or biscuitroot species endemic to the Great Plains and western U.S. Its seeds are reported to be used as a "love medicine," a unique use compared to other Lomatium species, which are primarily used as a root food and for broad health improvement. We harvested L. foeniculaceum plants from their natural habitat throughout the year and analyzed tissue and seasonal variations in their chemical composition to elucidate the relationship between traditional usage and the plant's metabolism and time of year, and how this might relate to its traditional usage. This species grew vegetatively from March to May and flowered in May and June. The aerial tissues senesced in July, and the root remained dormant from July to March. Leaves and flowers contained significantly higher levels of metabolites than roots. We detected two major essential oil constituents, (E)- and (Z)-ligustilide, and the furanocoumarin, bergapten, at high levels in leaves and flowers. L. foeniculaceum is an uncommon species accumulating less-stable E-form at higher concentrations than the Z-form. This characteristic essential oil composition is probably related to the fragrance of flowers and seeds. On the other hand, the roots of this species contained lower levels of bioactive compounds and nutrients, which, coupled with their toughness and stringiness, make them less desirable as food than those of other Lomatium species.