Classical Latin name probably derived from Jovis glans, the nut of the Roman god Jupiter of mythology.
Deciduous trees. Bark furrowed. Branchlets with partitioned pith. Buds scaly. Leaves alternate, pinnate, the leaflets toothed or entire. Flowers unisexual. Male flowers in pendulous catkins. Female flowers in short spikes. Fruits (walnuts) solitary or in clusters, the hard shelled, 2-chambered nut is contained within a fleshy husk.
The Royal Tasmanian Botanical Gardens has a small collection of mature species. The walnut has a long history in Australia with early plantings in Hobart, Tasmania in 1820 and many stands were established elsewhere in the 19th century including, in Victoria, fine trees still standing at Beechworth, Bright and Wandiligong thought to be associated with the gold mining era. The first recorded commercial plantation is probably that of Mr G. Monaghan of Brookside in the Buckland Valley in the early 1870s. Later, in the early 1900s the Wandiligong Nut Company was established in Morse's Creek Valley, Wandiligong and, at 40 ha was the largest commercial plantation in Australia.
Only in the 1920s were grafted cultivars used instead of seedlings. Perhaps the most renowned plantation in production today is at Gapsted, near Myrtleford in Victoria which was named Valley Nut Groves by the founders Abe and Henry Schlapp who established this enterprise in the early 20th centry. Most plantations are in Victoria in the river valleys of NE Victoria and E Gippsland although other small plantations may be found in W Gippsland, the Dandenongs and in New South Wales sites in the Blue Mountains, also elsewhere in the Adelaide Hills and Riverland of South Australia, as well as Tasmania and SW Western Australia. However, importation still exceeds Australian production which stands at about 120-150 tonnes. Commercially produced walnuts fall into three groups: Black Walnuts, Butternuts and Persian or Carpathian Walnuts. The major species used is J. regia which is grafted onto Royal hybrid (J. hindsii × J. nigra) or Paradox hybrid (J. hindsii × J. regia) rootstocks.
Edible nuts and attractive timber; oils are extracted from the nuts of some species to be used in soaps and paints; the yellow acid is used in dyes and stains.
Leaves and fruit bitter-smelling due to the picric acid which produces a yellow stain on the hands; pith partitioned.
About 20 species from N and S America, Europe and E Asia.
Allen (1986), Krüssmann (1986).
Source: (1997). Juglandaceae. In: . Horticultural Flora of South-eastern Australia. Volume 2. Flowering plants. Dicotyledons. Part 1. The identification of garden and cultivated plants. University of New South Wales Press.
