Over the past several years our research has focussed on the natural product chemistry of native North American prairie plants that have been reported in the ethnobotanical literature to have been used as medicines by Native North Americans and early European settlers. We have collected over 70 species of these plants from various prairie regions of the Midwest. The plants have been subjected to bioassays for activity against Mycobacterium tuberculosis, in-vitro HIV l and in-vitro human tumor cell lines. Recently we have begun to evaluate these plants as sources of immune enhancing food supplements. This presentation will discuss the chemistry of the prairie plant Silphium laciniatum associated with its anti-tuberculosis activity. We will also discuss our preliminary results with an in-house assay that we have developed to evaluate teas and tinctures of prairie plants as sources of nutritional supplements.