Alkaloid-Poor Plant Families, Poaceae and Cyperaceae, Are Over-Utilized for Medicine in Hawaiian Pharmacopoeia

Abstract

The theory of non-random medicinal plant selection predicts that the number of medicinal plant species in a given family is related to the total number of species in that family. As a consequence of such a strong relationship, some plant families are over-utilized for medicinal purposes while others are not. Medicinal plant families that are often over-utilized share evolutionary traits such as the presence of secondary plant compounds which are known to have medicinal values. Consistent with this model, several studies have shown that alkaloid-poor plant families such as Poaceae and Cyperaceae, two families known more for their physical defenses rather than their chemical defenses, are medicinally under-utilized across the world. In this study, we demonstrate that contrary to expectation, Poaceae and Cyperaceae are over-utilized in the Hawaiian ethnopharmacopoeia. One reason for this over-utilization is a result of the Hawaiian cultural practice of converting plants in the Poaceae and Cyperaceae families into ash for direct medicinal use or as a component in other medicinal preparations. The over-utilization of Poaceae and Cyperaceae is also potentially due to their versatility and greater availability in parts of the land divisions where most humans are allowed to visit. Knowledge of how to use ash is taught through mo‘olelo, Hawaiian history, and represents a Native Hawaiian understanding of and relationship to chemical knowledge. Our study provides new evidence for the theory of non-random medicinal plant selection and shows, contrary to expectation, that unique patterns of plant family over-utilization could arise in unique cultural and geographical contexts.