Currently various scientific and popular sources provide a wide spectrum of ethnopharmacological information on many plants, yet the sources of that information, as well as the information itself, are often not clear, potentially resulting in the use of plants among lay people or even in official medicine that may be misleading. Our field studies in seven countries on the Eastern edge of Europe have revealed an unusual increase in the medicinal use of Epilobium angustifolium L., especially in Estonia, where the majority of uses were specifically related to "men's problems". THE AIM OF THE CURRENT WORK IS: to understand the recent and sudden increase in the interest in the use of E. angustifolium in Estonia; to evaluate the extent of documented traditional use of E. angustifolium among sources of knowledge considered traditional; to track different sources describing (or attributed as describing) the benefits of E. angustifolium; and to detect direct and indirect influences of the written sources on the currently documented local uses of E. angustifolium on the Eastern edge of Europe.In this study we used a variety of methods: semi-structured interviews with 599 people in 7 countries, historical data analysis and historical ethnopharmacological source analysis. We researched historical and archival sources, and academic and popular literature published on the medicinal use of E. angustifolium in the regions of our field sites as well as internationally, paying close attention to the literature that might have directly or indirectly contributed to the popularity of E. angustifolium at different times in history.Our results show that the sudden and recent popularity in the medical use of E. angustifolium in Estonia has been caused by local popular authors with academic medical backgrounds, relying simultaneously on "western" and Russian sources. While Russian sources have propagated (partially unpublished) results from the 1930s, "western" sources are scientific insights derived from the popularization of other Epilobium species by Austrian herbalist Maria Treben. The information Treben disseminated could have been originated from a previous peak in popularity of E. angustifolium in USA in the second half of the 19th century, caused in turn by misinterpretation of ancient herbals. The traditional uses of E. angustifolium were related to wounds and skin diseases, fever, pain (headache, sore throat, childbirth), and abdominal-related problems (constipation, stomach ache) and intestinal bleeding. Few more uses were based on the similarity principle. The main theme, however, is the fragmentation of use and its lack of consistency apart from wounds and skin diseases.Historical ethnobotanical investigations could help to avoid creating repeating waves of popularity of plants that have already been tried for certain diseases and later abandoned as not fully effective. There is, of course, a chance that E. angustifolium could also finally be proven to be clinically safe and cost-effective for treating benign prostatic hyperplasia, but this has not yet happened despite recent intensive research. Documented traditional use would suggest investigating the dermatological, intestinal anti-hemorrhagic and pain inhibiting properties of this plant, if any.
