Wild tomatillos (Physalis species) as food and medicine

An ethnobotanical perspective can contribute to the discovery of new medicines and drugs from plant biodiversity. With interest in withanolides, a group of anti- proliferative compounds in the Indian plant ashwaganda, Withania somnifera, our research team wanted to determine if any native US plant species might contain these or other compounds with similar structures. Withania is in the Solanaceae, so we considered plants in the genera of Solanum, Datura, and Physalis. As part of our Native Medicinal Plant Research Program, we have developed an extensive ethnobotanical database which lists all the edible and medicinal uses of plants in the Great Plains and Midwest. All of these Solanaceae genera had useful species, and we picked those species to explore further for biological activity. With work conducted in the Timmermann lab, we have found the longleaf groundcherry or wild tomatillo, Physalis longifolia, to have not only withaferin A, but also a large number of bioactive withanolides including several new structures. As a closely related group of Physalis species, the 29 wild tomatillo species found north of Mexico have been an important wild-harvested food and medicinal plant. I will discuss the traditional uses for food and medicine, and confusing taxonomic difficulties of this group. Subtle morphological differences recognized by taxonomists to distinguish these related taxa are confusing to botanists and ethnobotanists, and these differences are not recognized as important by native peoples. The importance of wild Physalis species is documented by at least 23 tribes using them as food, and its long history of use is evidenced by its discovery in at least 19 archaeological sites where it is often found in carbonized remains in the hearths where they were cooked. These sites, which date from the Archaic to the Classic period, stretch from the Rio Grande Valley in New Mexico and from southwest Colorado through the Great Plains and the Midwest and into Ontario, Canada and North Carolina in the east. Physalis species have tasty fruits and were collected from the wild and were encouraged in agricultural fields, and possibly even cultivated. In historic times and up to the present, these plants may have been cultivated by Pueblo farmers and other tribes of the US Southwest. They were used as food and medicine, but the primary use has been as food. Even today, the Pueblo people cook the wild tomatillo fruit and make them into a green sauce similar to commercial preparations. When found abundantly, they were dried for later use in soups and food. Due to the abundance of seeds in some species and in some archeological sites, it appears that the seeds might also have been dried, ground into powder and used in soups and stews. The importance of this significant food use over an extensive period of time provides some sense of the safety of use of this plant, and of its desirability. When dried, the fruits become sweeter and taste somewhat like a dried cranberry, with a slight tomato flavor. Although less important than food uses, Native American medicinal uses of Physalis were also common, including use by the Omaha, Ponca, and Winnebago to treat headache and stomach trouble, and as a dressing for wounds. Recent work by our research program shows that there are many withanolides within the plant and fruit, some of which have potent anti-proliferative activity. Due to the numerous, extensive, and long term uses of the fruits as food, it appears that they are safe to consume. Although this common plant is widely ignored and described as a weed, it was once an important plant for both food and medicine, and may be so again.