Juglans mandshurica other popular "Juglans" species and usually causes few significant allelopathic effects in cultivation. "Juglans cathayensis", characterized by tomentose leaflets, producing more flowers per spike and growing south of the Yellow River, was sometimes recognized as a species separate from "J. mandshurica". The Japanese walnut ("oni-gurumi") is listed by some authorities as "Juglans mandshurica" var. "sachalinensis" (syn. "Juglans ailantifolia") Juglans mandshurica Juglans mandshurica, the Manchurian walnut, is a deciduous tree of the genus "Juglans" (section "Cardiocaryon"), native to the Eastern Asiatic Region (China, Russian Far East, North Korea and South Korea). It grows to about 25 m. The leaves are alternate,
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