Japanese walnut is a Far Eastern species which, given full sun and moist rich soil, grows into a mid-sized to large tree with a broad crown. Impressively large pinnate leaves made up of leaflets that can grow to 80 cms (32 inches). The fruit is an edible round nut about 4 cms long, covered by a hard shell.
The Japanese and its close relative the Manchurian walnut (J. mandshurica) are so similar that even experts have problems distinguishing them. The only clear difference is between the nuts: the Japanese is round, the Manchurian oval.
True Japanese walnut grows at Mustila only as young trees, along the path leading from Puistokahvila (Arboretum Café) to Pähkinärinne (Hazelnut slope). These were planted as six-year-olds in 1999, from seed of Khabarovsk provenance.