noix (French), Walnufs (German), noce (Italian), nuez (Spanish), noz (Portuguese), gretskiy/orekh (Russian), karithis (Greek), ceviz (Turkish), gerdoo (Persian), charmaz (Afghanistan), hu tao (Chinese), kurumi (Japanese)
(Juglans regia, J. nigra – Family Juglandaceae)
Walnuts are related to the pecans and hickories and comprise about fifteen species native to various parts of Asia and North and South America. There are twenty-five different kinds of hickories, including the pecan, scattered throughout eastern Asia and eastern North America. The most important species is the Persian walnut (J. regia), which is often called the English walnut. Despite its name, the natural range of the English walnut extends from the Himalayas through Iran, Lebanon and Asia Minor, and into Greece. Walnut trees were not introduced into Britain until the middle of the 15th century, but, since that time, though, heavy cutting for timber has depleted their numbers. “English” is not the only prefix to have been used when introducing the walnut. Others have included: Persian, Royal, Italian, Madeira, European, French, Chile, Caucasian, Circassian, and Manchurian.
The fruit is a green drupe, with flesh surrounding a hard-shelled stone or nut. Inside the nut is the edible kernal. When the fruit is very young and green, the fleshy outside can be eaten. This is the time when the shell is undeveloped, so the entire fruit is edible although sour in taste. These half-ripe walnuts are preserved in syrup in the Middle East, and, to many, are considered the most delicious form these nuts take. As the fruit ripens, the fleshy part becomes thin and leathery. The shell consists of halves separated by a papery, inedible membrane. The division is clearly marked by a seam around the outside edge. The half-kernels are convoluted like “brains,” and, in Afghanistan, the word for walnut means four brains (charmarghz).
Walnut trees have grown both in the wild and in cultivation from Greece and the Caucasus to Japan at elevations up to 10,000 feet. According to Pliny, the walnut tree was introduced into Italy from Persia. Varro, who was born in 116 BCE, mentions it as existing in Italy before his time. In North China, an almost huskless variety of walnut exists. The titmouse variety, grown in France, received its name from the bird. This variety of walnut has shells so thin that birds, especially the titmouse, can break into it and eat the kernels.
In many parts of Spain, France, Italy, and Germany, the nuts form an important article of food, as well as a source of oil. France, especially, uses considerable quantities of walnut oil in cooking. Extracting the oil cannot occur until two or three months after the nuts have been gathered as the fresh kernel contains only an emulsive milk and not an oil. During this period, the oil continues to form, gradually replacing the milk. However, if too much time elapses, the oil becomes less sweet and leans toward rancidity. The first pressed oil is termed “virgin” and reserved for food purposes. The cake-residue is then rubbed down in boiling water and pressed again. This pressing is labelled “fire-drawn” and used for industrial purposes.
The edible nuts are as much sought after as the tree’s timber, especially the black walnut native to North America. To a lesser extent, the butternut and the Japanese walnut are also valued for their wood grain. Various other timbers are sometimes described as walnut, including satin walnut from the US, the yellow walnut (Beilschmiedia bancroftii), African walnut (Coula edulis – Family Olacaceae), East Indian walnut or kokko from the Andaman Islands, Brazilian nutmeg (Cryptocarya moschata), and Queensland walnut (Endiandra palmerstoni – Family Lauraceae) from Australia; but only the Juglans species are true walnuts.
The Walnut family has several genera scattered throughout the remote parts of the world, including: Alfaroa (one species in Costa Rica), Engelhardtia (five species from the Himalayas to Formosa), Oreomunnea (three kinds in Mexico and Central America), Platycarya (two species in eastern Asia), and Pterocarya (ten kinds from the Caucasus to Japan, including P. caucasica of the Orient which produces an edible nut)
Some of the common walnut species include:
– The American black walnut (Juglans nigra) originally belonged to the eastern half of the US and Canada and has been prized for more than 200 years for its beautiful wood. The nut has a thick blackish-brown shell and a strong, but pleasant, flavour. This also applies to the butternut or American white walnut (J. cinerea) which also grows in the eastern half of the country. Among the South American species are the Bolivian black walnut (J. boliviana), which bears good quality nuts, as does the Ecuador walnut or “nogal” (J. honorei).
– Chinese walnut, mountain walnut, Cathay walnut (Carya cathayensis) is a tall deciduous tree that grows in China. The fruit is globular to oblong with a four-angled outer layer. Another walnut tree native to China is the Manchurian walnut of the north (J. mandshurica).
– Butternut, American white walnut (J. cinerea) is very rare, but its nuts are one of the best for flavour, although it is more oily. The tree looks like a black walnut, except that the trunk has a whitish cast in its higher regions. Another important difference is that the butternut hulls do not stain the fingers like the black walnut. The Narragansett Indians called it “wussoquat.” The oil from the seeds was used for their seasoning. The nut paste was used to thicken their pottage, and the immature fruit, pickled.
– The California walnut (J. californica) is native to that state.
– Japanese walnut, heartnut (J. sieboldiana or ailanthifolia) is a small nut with a good flavour. This species is now cultivated in the US under the name of “heartnut” because of the shape of the hulls and the kernels. The 60-foot tree, which bears its fruit in the fall, is endemic to Japan, where it grows along streams an on wettish plains. The Japanese use the hulls in treating fish poisonings.
– Yellow walnut, wanga (Beilschmiedia bancroftii – Family Lauraceae) is not a true walnut, but consists of some 200 kinds that grow in tropical Australia and New Zealand. This species produces a large seed and, after treatment, provides the most flavoured source of flour among the aborginals of the rain forest. Another species, commonly called Tola or Spicy Cedar, produces seeds that are sometimes confused with the Bitter Kola, but are readily distinguishable as they separate into two cotyledons. They are somewhat oily but used in food or ground and roasted and used to enrich native dishes.
– Queensland Walnut (Endiandra palmerstonii – Family Lauraceae) is not a true walnut but is a member of a genus that has about eighty species found in Malaysia, Australia, and Polynesia. The kernels are ground and used as flour.