Juglans regia variations in fatty acid content of the nuts: Walnuts and other tree nuts are important food-allergen sources that have the potential to be associated with life-threatening, IgE-mediated allergic reactions in some individuals. Certain extracts of walnuts have "in vitro" antioxidant and antiproliferative activity due to a high phenolic content. "Juglans regia" is used to treat Diabetes mellitus symptoms in Austrian traditional medicine, whereby air-dried leaves are used as aqueous decoction or liquor preparation and are consumed on a daily basis. In Skopelos, a Greek island in the Aegean Sea, local legend suggests whoever plants a walnut tree will die as
Juglans californica "J. californica" grows in riparian woodlands, either in single species stands or mixed with California's oaks ("Quercus" spp.) and cottonwoods ("Populus fremontii"). "Juglans californica" can be either a large shrub with 1–5 trunks, or a small, single-trunked tree. The main trunk can fork close to the ground, making it look like two trees that have grown together, then diverged. It has thick bark, deeply channeled or furrowed at maturity. It has large, pinnately compound leaves with 11–19 lanceolate leaflets with toothed margins and no hair in the vein angles. It has a small hard nut in a shallowly grooved, thick