[Previous spelling as "quinquefolium" was incorrect (W, Y).] P. quinquefolius is widespread across eastern North America, but rare to absent on the southeastern Coastal Plain; itsrange is similar to that of Hydrastis but more extensive (K). This medicinally potent herb is still widely scattered over Ky., usually on medium- to slightly acid soils (with pH 5-6.5) in mesic to somewhat subxeric woods. A detailed study in Pa. indicated the following most commonly associated trees (Burkhart 2013): Acer saccharum (dominant), Liriodendron, Fraxinus americana, Tilia americana. Common understory species included: Parthenocissus, Lindera, Viburnum acerifolium, Hamamelis, Toxicodendron, Ostrya (woody); Arisaema triphyllum, Polygonatum pubescens, Circaea, Polystichum, Galium triflorum, Botrypus, Podophyllum, Maianthemum, Ageratina (herbs). However, intense repeated harvesting has continued to reduce its density, initially in more agricultural landscapes then more recently in Appalachian regions with economic troubles. Even in the best habitats, a day of general botanical survey rarely reveals more than 5-10 plants. Yet Ky. Is reported to have a relatively high annual harvest, estimated to be about 30,000 lbs (dried) in 2007, some of which may be cultivated (International Herald-Tribune (2007); much is also harvested in the Ozark region (Y), Wisconsin and eastern Canada but accurate statiistics have been hard to compile (fws.gov/international/ plants/american-ginseng.html). Although harvest is regulated by federal and state governments, Illegal harvesting continues to be prevalent (McGraw et al. 2010). The chemicals of central interest in Panax are "ginsenosides" that are tetracyclic triterpenes (sapogenins) with diverse therapeutic uses (e.g. Mancuso & Santangelo 2017). These specific chemicals are known only from Panax, but there are similarities to the "dammarane-type" triterpenoid saponins in some Dipterocarpaceae, Burseraceae, Rosaceae and Veronicaceae (Poehland et al. 1987, Garai et al. 1996); and to the "withanolide" steroids of some Solanaceae (Chen et al. 2010).