THE TOXICITY OF EXTRACTS OF TEPHROSIA VIRGINIANA: (FABACEAE) IN OKLAHOMA

Historical usage of the roots of the legume Tephrosia virginiana as a piscicide by Native Americans has been documented. Due to questions about geographic variation in toxicity, an examination of the toxicity of six Oklahoma populations of the species was conducted. Rootstock extracts of plants in all populations exhibited acute toxicity in a standard laboratory bioassay using larval fathead minnows (Pimephales promelas). Isolation and identification of the compound or compounds responsible were not undertaken, however, toxicity is generally thought to be due to the presence of rotenone and related compounds. Although considerable variation in LC50 values exists among the six populations, this study produced few statistically significant differences. Correlations between plant toxicity and edaphic factors were not seen.