Juglans californica of the genus suggests "J. californica" is sister to the remaining black walnuts (section Rhysocaryon). This article follows the conventions of "The Jepson Manual". Juglans californica Juglans californica, the California black walnut, also called the California walnut, or the Southern California black walnut, is a large shrub or small tree (up to 30 feet tall) of the walnut family, Juglandaceae, endemic to California. "Juglans californica" is generally found in the southern California Coast Ranges, Transverse Ranges, and Peninsular Ranges, and the Central Valley. It grows as part of mixed woodlands, and also on slopes and in valleys wherever conditions are
Juglans olanchana Juglans olanchana Juglans olanchana is a semideciduous tree species in the Juglandaceae family. It can be found in Costa Rica, Guatemala, El Salvador, Honduras, Mexico and Nicaragua. It can grow up to 40 m in height and 1.5 m in diameter. The long branches bear twigs tipped with 40–50 cm long, glabrous, pinately compound leaves, darker on the top than on the bottom. The base of the trunk sometimes has buttresses. "Juglans olanchana" grows in wet and very wet tropical forests, most frequently on river banks, observed from 0–1400 m above sea level. Reports that it also grows in the