Chestnut

• 1. Introduction

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  Chestnut trees belong to the genus Castanea, and the most famous of them grows on the slopes of Mount Etna. The Hundred Horse Chestnut measured 57.9 metres, or 190 feet, in circumference in 1780. By 1883 the figure had reached 64 metres. It is counted as the oldest living chestnut tree.

  One tree like that hints at how much a chestnut can mean to a place. Chestnuts have been food, timber, medicine and a symbol, sometimes all at once. They have also been loved, scorned and nearly lost.

  This documentary follows several questions. Why did mountain villagers once rely on a nut for most of their carbohydrates, and why did the same nut earn a reputation as food for the poor? Where does the odd word chestnut come from, and which unrelated plants have borrowed it? What happened to the great chestnut forests of eastern North America? And what does it take to grow a chestnut orchard today, with so many insects and fungi in the way?

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• 2. Anatomy of a Chestnut

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  The sweet chestnut, Castanea sativa, is the tallest of the genus, reaching 35 to 36 metres. The American chestnut, C. dentata, climbs to around 30 metres. The Chinese chestnut, C. mollissima, tops out near 15 metres, and the Japanese chestnut, C. crenata, averages about 10. The smallest members are the chinkapins, which are often just shrubs. Growth speed varies too. The Chinese species grows at a moderate pace, while the American and European species grow fast.

  Chinese and Japanese chestnuts are often multistemmed and wide-spreading. The sweet and American chestnuts behave differently among neighbours. They grow very erect, with massive, firmly set trunks that barely taper. Standing alone, they spread sideways into broad, dense, rounded crowns. In autumn the foliage of the European and American species turns a striking yellow.

  Maroon or red-brown bark marks a young American chestnut, while a young sweet chestnut has grey bark. With age the bark darkens, thickens and cracks into deep furrows. The furrows run lengthwise and twist around the trunk, sometimes resembling a large cable of twisted strands. The leaves are 10 to 32 centimetres long and 4 to 10 centimetres wide, with sharply pointed teeth set far apart.

  Chestnut flowers open after the leaves, in late spring or early summer and sometimes into July. Every tree carries two kinds of long catkin. Catkins of male flowers alone mature first. Each male flower has eight stamens, or 10 to 12 in C. mollissima. The pollen has a heavy, sweet smell that some people find unpleasant. The second kind of catkin also carries male flowers, but near the twig it holds small clusters of female flowers. Two or three of these join inside a four-lobed prickly cup, which grows together into the husk around the fruit. A tree cannot pollinate itself, so two trees are needed. All Castanea species hybridize readily with one another.

  A spiny burr, 5 to 11 centimetres across, holds the nuts. It contains anywhere from one to seven, depending on species, variety and cultivar. As the fruit matures, the burr turns yellow-brown and splits into two or four sections. Most burrs release their nuts only after falling to the ground, helped along by soil humidity. Each nut has a pointed tip with a small tuft, which Italians call the flame. At the other end is a pale scar called the hilum. Two skins wrap the creamy-white flesh. The hard, shiny outer one is the pericarpus, which the industry calls the peel. The thin inner one is the pellicle, which clings to the seed along its grooves.

  Cultivars with one large, well-rounded nut per burr often carry the name marron, as in marron de Lyon in France or Marrone di Mugello in Italy. A nut may sprout the moment it lands in autumn, sending out roots at once and leaves the following spring. If it dries out, it soon loses its ability to grow.

  Botanists sort the chestnuts into four main groups, the American, European, Chinese and Japanese chestnuts. All sit in the beech family Fagaceae, alongside oaks and beeches. The classification is not fully settled. The Ozark chinkapin, Castanea ozarkensis, and the Allegheny chinkapin, Castanea pumila, are sometimes treated as one species. Castanea alabamensis may also be a valid species.

  Nut size shows how far the groups differ. American chestnuts are small, around 5 grams, but sweet with pellicles that peel easily. Some Japanese cultivars reach about 40 grams, though their pellicles are typically hard to remove.

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• 3. Names and Impostors

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  The Old French word chastain, châtaigne in modern French, gave English its earlier phrase chesten nut. The French word comes from the Latin Castanea, which is also the tree's scientific name. Latin in turn took it from the Ancient Greek κάστανον, meaning sweet chestnut.

  One possible source for the Greek word is Casthanaea, an ancient town in Magnesia, at the site of the modern village of Keramidi. The town probably took its name from the trees growing around it. Chalky soil makes chestnuts rarer in Greece. Kastania sits on one of the few sedimentary or siliceous outcrops, and trees grow there so abundantly that they would have named the place.

  A rival theory points to the Greek name Sardis glans, meaning Sardis acorn. Sardis was the capital of Lydia in Asia Minor, the place from which the fruit is said to have spread.

  The King James Version of the Bible names the tree twice. In one passage Jacob places peeled twigs in the water troughs to encourage healthy offspring among his livestock. The word may refer to another tree. Even so, it suggests the nut was a familiar local staple in the early 17th century.

  In 1753 Linnaeus called the tree Fagus castanea in the first edition of Species Plantarum. Other names have included Sardian nut, Jupiter's nut and husked nut. Americans also call the sweet chestnut the Spanish chestnut.

  Several plants borrow the name without the family ties. The horse-chestnuts, genus Aesculus, are unrelated to true chestnuts. Their nuts look slightly similar but are mildly poisonous to humans. Water chestnuts are tubers of an aquatic plant in the sedge family Cyperaceae. The chestnut oak, Quercus prinus, and the American beech, Fagus grandifolia, do belong to the beech family. They are still sometimes mistaken for chestnut trees.

  Brazil nuts add one more case. Spanish speakers call them castañas de Brasil, and Portuguese speakers say castanha-do-Pará, meaning chestnuts from Pará. They are unrelated as well.

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• 4. Bread of the Mountains

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  Evidence of human cultivation of chestnuts reaches back to around 2000 BC. For millennia the nut was a staple in southern Europe, Turkey, and southwestern and eastern Asia. In mountainous Mediterranean areas, where cereals grew poorly or not at all, it largely took their place. Alexander the Great and the Romans planted chestnut trees across Europe during their campaigns.

  A Greek army is said to have survived its retreat from Asia Minor in 401-399 BC thanks to its stores of chestnuts. The Greek writers Dioscorides and Galen discussed the nut's medicinal properties, and the gas that eating too many of them produces. The early Christians took the chestnut as a symbol of chastity.

  Until the potato arrived, whole forest communities with little access to wheat flour depended on chestnuts for their carbohydrates. In 1583 Charles Estienne and Jean Liébault wrote, "an infinity of people live on nothing else but (the chestnut)". In 1802 an Italian agronomist said of Tuscany that "the fruit of the chestnut tree is practically the sole subsistence of our highlanders". By 1879 it was said to feed whole populations almost exclusively for half the year, as "a temporary but complete substitution for cereals".

  Rulers planned for it too. In 1584 the governor of Genoa, which dominated Corsica, ordered every farmer and landowner to plant four trees a year. The chestnut was one, alongside the olive, the fig and the mulberry. Many communities owe their origin and former richness to the chestnut woods that followed.

  The numbers explain the appeal. A 100-gram portion of raw chestnut supplies 200 calories, with 44 grams of carbohydrate, 2 of protein and 1 of fat. That carbohydrate level compares with wheat and rice, and chestnuts hold twice as much starch as a potato. In some areas the sweet chestnut is called the bread tree.

  Ripeness changes the nut. Young fruit are mostly starch and feel firm because of their high water content. As they ripen, the starch slowly turns into sugar and the moisture drops. A ripe chestnut gives slightly under a finger, because space opens between the flesh and the hull. Chestnuts are also among the few nuts that contain vitamin C, at 48 percent of the Daily Value per 100 grams. Heating cuts that amount by roughly 40 percent.

  Popularity fell over the last few centuries, partly because of the label food for poor people. Many refused to call chestnut bread real bread, since chestnut flour does not rise. A writer in 1770 claimed it "gives a sallow complexion". In 1841 another dismissed chestnut soup as "this kind of mortar which is called a soup".

  In Honoré de Balzac's novel Père Goriot, the character Vautrin remarks that the family of Eugène de Rastignac is living off chestnuts. The detail is there to show how poor they are.

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• 5. Feasts and Far Shores

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  In 1882, at Privas, a civil engineer named Clément Faugier invented a way to make marrons glacés on an industrial scale. Lyon had fallen into recession toward the end of the nineteenth century, when the silk-led textile market collapsed. Faugier was looking for a way to revive the regional economy.

  Marrons glacés are whole chestnuts candied in sugar syrup and then iced. They appeared in France in the sixteenth century, and the Turkish name for them is kestane şekeri, meaning sugared chestnuts. Many of the more than 20 steps from harvest to finished product are still done by hand. Chestnuts are picked in autumn and candied from the start of the following summer. The marrons glacés eaten at Christmas were therefore picked the year before. In France they are always served at Christmas and New Year.

  Italian tables hold regional customs. In Modena, chestnuts are soaked in wine before roasting. Tuscany eats them traditionally on Saint Simon's Day. In the Romagna region, roasted chestnuts come with a traditional wine, the Cagnina di Romagna. In Portugal, roasted chestnuts mark St. Martin's Day, and on the island of Madeira a chestnut liquor is a traditional drink.

  On the 31st of October, the eve of All Saints' Day, Catalonia celebrates la castanyada. The feast centres on chestnuts, panellets, sweet potatoes and muscatell. In November, Galicia, Asturias, Cantabria and other northern provinces, along with Portugal, hold the Magosto.

  Hungarian cooks make gesztenyepüré by puréeing cooked chestnuts with sugar and usually rum. They force the mixture through a ricer and top it with whipped cream. A Swiss version made with kirsch and butter is called vermicelles, and the French version is known as Mont Blanc.

  In Corsica, chestnut flour becomes polenta, called pulenda there, and doughnut-like fritters called fritelli. It is also made into necci, pattoni and cialdi. The flour from Castagniccia is light beige, while other regions produce darker flour. Chestnut bread can stay fresh for as long as two weeks.

  The famous potato promoter Parmentier extracted sugar from chestnuts. He sent a chestnut sugarloaf weighing several pounds to the Academy of Lyon. The continental blockade of 1806-1814 increased research into chestnut sugar, but Napoleon chose beets instead.

  In Japan, the chestnut called kuri was in cultivation before rice. It is always part of the New Year's menu, where it stands for both success and hard times, mastery and strength. The Chinese chestnut has possibly been cultivated for 2,000 to 6,000 years. China today has about 300 cultivars, and the Dandong chestnut, a Japanese chestnut, is a major cultivar in Liaoning Province.

  In South Korea, roasted chestnuts called gunbam are a popular winter snack and a symbol of abundance in ancestral rituals. Korean folk songs include Gunbam Taryeong, which celebrates chestnuts, and Jeongseokga, a song from the Goryeo period. Gongju, a former capital of Baekje, is renowned for its chestnuts and holds an annual chestnut festival in winter. The Samgukji, a record of the Three Kingdoms compiled during the Jin dynasty, uses chestnuts to describe Mahan, the former land of Baekje.

  In the Philippines, imported chestnuts called kastanyas, from the Spanish castañas, are traditional Christmas street food. English-language Christmas tradition has its own chestnut line. The opening of The Christmas Song mentions them, and the song is commonly subtitled Chestnuts Roasting on an Open Fire. In 1939 the composer Jaromír Weinberger wrote Under the Spreading Chestnut Tree, a set of variations with fugue for orchestra.

  British colonial rule in India, from the mid-1700s to 1947, brought the sweet chestnut to the temperate lower and middle Himalayas. It grows widely in British-founded hill stations in northern India, and less so in Bhutan and Nepal. It serves mainly as an ornamental tree in botanical gardens and the compounds of larger official residences.

  The Australian gold rush of the 1850s and 1860s brought the first recorded plantings of European chestnuts, carried over by settlers. Some trees in northern Victoria are around 120 years old and up to 60 metres tall. As of 2008 the country had nearly 350 growers producing about 1,200 tonnes a year, 80 percent of it from northeast Victoria. The Japanese chestnut reached New Zealand in the early 1900s, mostly in the upper North Island.

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• 6. The American Blight

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  In the Appalachian Mountains, one in four hardwood trees was a chestnut. Mature trees often grew straight and free of branches for 50 feet, sometimes up to 100, and averaged as much as 5 feet across. For three centuries most barns and homes east of the Mississippi River were built from the wood. Native Americans had eaten the nuts long before European immigrants brought their own stock.

  A food reference book of 1911 noted that a cannery in Holland sold a ready-cooked casserole of chestnuts and sausages next to classic beef and onions. The entry celebrated a chestnut culture that sent whole villages into the woods for three weeks each autumn and kept them busy all winter. It also regretted how little variety American shops stocked.

  Then came 1904, when the discovery of a blight fungus on Asian chestnut trees planted on Long Island, New York, was made public. The fungus is Cryphonectria parasitica, formerly Endothia parasitica. East Asian chestnuts evolved alongside it and are moderately to very resistant. European and North American species had never met it and have little or no resistance. European and West Asian chestnuts are less vulnerable than the American ones, and the American chinkapins are very susceptible.

  Within 40 years the American chestnut population, nearly four billion trees, was devastated. Only a few clumps remained in Michigan, Wisconsin, California and the Pacific Northwest. The tree that had been the most important on the East Coast shrank to an insignificant presence.

  American chestnut wood almost vanished from the market for decades, though reclaimed lumber can still be found. The living trees survive as rare single specimens far from any others, or as living stumps called stools. Only a few stools grow enough shoots to produce seed shortly before dying. That is just enough to preserve the genetic material needed to engineer an American chestnut with the least possible input from disease-immune Asian species.

  Efforts to repopulate the country began in the 1930s and continue in Massachusetts and many other places. Huge reforestation efforts in the United States that decade also tried to establish blight-resistant cultivars of C. sativa, and they may have helped renew interest in the nut worldwide. In the 1950s Robert T. Dunstan developed the Dunstan chestnut in Greensboro, North Carolina. It makes up the majority of the blight-free chestnuts the United States produces each year.

  In the 1970s the geneticist Charles Burnham began back-breeding Asian chestnut into American chestnut populations. The aim was to confer blight resistance with the smallest possible difference in genes. The American Chestnut Foundation, working with partners including SUNY ESF and the American Chestnut Cooperators' Foundation, is in the last stages of developing a variety as close as possible to the American chestnut that carries the resistance gene of the Asiatic species.

  Meanwhile, demand for the nut outstrips supply. In 2007 the United States imported 4,056 tonnes of European in-shell chestnuts worth $10 million. The American industry is in its infancy and produces less than 1 percent of the world total. Since the mid-20th century most imports have come from Southern Italy. Large, meaty, richly flavoured Sicilian chestnuts are considered among the best for bulk sale and supermarket retail. Portugal and France also supply some, and China and South Korea are the next two largest sources. As of 2024 the country imports 7.5 million pounds of non-organic chestnuts a year.

  A study of the sector in 2005 found that American producers are mainly part-timers or hobbyists. Most earn less than $5,000 per year, and a third had not yet sold anything, because most orchards are under 10 years old. A ten-year-old tree is conservatively assumed to yield 10 kilograms, though exceptional specimens have yielded 100. Another study suggests a new plantation needs 13 years to break even, at least in the current Australian market.

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• 7. Orchards and Their Enemies

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  Chestnuts produce better crops after a cold dormant period, so frosts and snowfalls help the trees. In Britain the dormant plant is hardy to the Royal Horticultural Society's H6 rating, down to -20 °C, and it grows well as far north as northern Scotland. Spring is riskier. Young growth is frost-tender even on mature plants, and bud-burst comes later than in most fruit trees, so late frosts can still damage the buds.

  Trees are found between 200 and 1,000 metres above sea level, though the Etna giant stands higher, at 1,200 metres. They tolerate maritime exposure, with reduced growth. Seeds germinate in late winter or early spring and do not live long. Sowing them soon after they ripen is better, because stored seeds must be checked regularly for sprouting. Seedlings need protection from cold in their first winter, and from mice and squirrels.

  A soil pH of 5.5-6.0 suits chestnuts best. They thrive on soils derived from granite, sandstone or schist, but dislike alkaline ground such as chalk. On alkaline soils, growers graft chestnuts onto oak rootstocks. Deep, sloping, well-drained ground is ideal, while shallow soils and heavy clay subsoils are not. The Chinese chestnut copes even with fairly dry, rocky or poor ground. Recently cleared land is best avoided, because it invites the root rot caused by the honey fungus Armillaria mellia, which is worse on heavy, poorly drained soil.

  An experiment in Ohio with C. dentata seedlings confirmed that chestnuts need full sun. Growers sometimes paint the base of the trunk white to prevent sunburn until the canopy develops. Where trees touch, virtually no fruit is produced. Industrial plantings range from 7 by 7 to 20 by 20 metres. The closer spacings are more popular because production rises sooner, but they later demand heavy pruning or tree removal.

  The best rainfall is 800 millimetres or more, spread evenly through the year. Below 700 millimetres, a drip irrigation system should make up the difference. Once established, the trees resist drought well.

  Grey squirrels start stripping bark when a tree is about eight years old and keep at it for the rest of its life. Rabbits and wallabies can do great damage to young trees. In Australia the sulphur-crested cockatoo damages branches up to 10 millimetres thick by carrying out "beak maintenance" on young trees. In New Zealand the grass grub beetle can entirely strip a young tree in late spring, flying at dusk, often in huge numbers.

  Among insects, Dryocosmus kuriphilus, the oriental chestnut gall wasp, is native to China but invasive elsewhere. It attacks and destroys the fruit, and it is considered the world's worst pest of chestnuts.

  In Hungary, the chestnut weevil Curculio elephas swarms in orchards around the 20th of August, most strongly at noon in sunny weather. Its larvae feed on the nuts and leave only nutchips and excrement inside. They can only chew their way out of a fallen nut, so picking up chestnuts as soon as they fall reduces the overwintering larvae. Planting an orchard beside a turkey oak forest is not advised, because the weevil also develops in turkey oak acorns. The acorn moth, Laspeyreisa splendana, causes about 5-41 percent of the damage in plantations in western Hungary.

  The disease called ink disease takes its name from the ink-black colour of tannic acid that oxidizes after seeping out of the tree. It attacks the roots and root collars, and the leaves turn yellow and fall. The fruit stay small, and the nuts drop prematurely from the burrs. In acute cases the roots decay and the trees dry out and wither away.

  Two pathogens, Phytophthora cambivora and Phytophthora cinnamomi, cause it. Phytophthora disease is the longest-known chestnut disease leading to tree death. Phytophthora cinnamomi was discovered in chestnut trees in the United States in 1932, and Phytophthora cambivora has been known in European chestnuts since 1971. Chemicals seem of little use, and many countries impose strict rules to prevent its spread.

  Leaf spot, caused by Mycosphaerella maculiformis, is the most common chestnut disease. Around June tiny white spots appear on the leaves, grow, and turn brown. By the end of summer the spots cover each leaf, which turns yellow. The chestnut mosaic virus is probably carried by the oak aphid Myzocallis castanicola.

  Trouble continues after harvest. In storage rot, a broken tuft is the most common entrance for fungal spores. The fungus Ciboria turns the flesh black and spongy. Parts of a nut with no colour change remain edible.

  For storage without refrigeration, there is an old method. Growers soak the nuts in cold water for about 20 hours right after harvest. Then they dry them in the shade and layer them in dry sand, which keeps them fresh for a few months.

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• 8. Wood and Tannin

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  Most chestnut timber comes from coppice systems cut on a 12-year rotation, which yield small timber that splits less than large logs. In southern England, particularly Kent, sweet chestnut has traditionally been coppiced and recut about every 10 years. The poles went to firewood and to fencing, including fence posts and chestnut paling.

  Chestnut belongs to the same family as oak, and its wood is rich in tannins as well. The tannins make it very durable outdoors without any added treatment, and they corrode iron slowly. Copper, brass and stainless metals are not affected. Young chestnut wood has proved more durable than oak for stakes and fences that sit partly in the ground. Older timber tends to split and warp when harvested, and it ends up neither as hard nor as strong as oak.

  Pollen records show that chestnut is an introduced tree in Britain, not a native one. It is associated with sites of Roman-era occupation, but it was already established by then. The tree grows so freely that it was long considered native. One reason was the belief that the roof of Westminster Hall and the Parliament House of Edinburgh were built from chestnut. Chestnut loses much of its durability once a tree passes 50 years old, and the beams in those roofs are far larger than any 50-year-old chestnut's girth. The roofs are in fact made of Durmast oak, which closely resembles chestnut in grain and colour.

  Britain's famous Tortworth Chestnut in South Gloucestershire was already a landmark in boundary records compiled in the reign of King John. By the days of Stephen it was known as the Great Chestnut of Tortworth. In 1720 it measured over 50 feet in circumference at 5 feet from the ground. In 1776 it was described as the largest tree in England, at 15.8 metres in circumference.

  Large chestnut beams are uncommon in buildings, but small outdoor pieces have always been prized. These include furniture, fencing, shingles for cladding buildings, and pit-props. In Italy, chestnut is used to make barrels for aging balsamic vinegar and some alcoholic drinks, such as whisky or lambic beer. In the French Cévennes, the 18th-century berles are cupboards cut directly from a hollowed trunk. In North America the long, unbranched trunks of the American chestnut made it an important source of lumber.

  Chestnut firewood spits on an open fire, so it is best burned in a closed log-burner.

  Before synthetic tannins, chestnut wood tanned leather. Dry bark holds 6.8 percent tannin and the wood 13.4 percent. The bark gives the tannin a dark colour and carries more sugar, so tanners used the wood. They extracted the tannin by hot-water extraction of chipped wood. Castalagin makes up 14.2 percent of it and vescalagin 16.2 percent. Its naturally low pH, low salt content and high acid content give it the astringency to fix raw hides. That makes it especially suitable for heavy hides and for the soles of high-quality shoes.

  Chestnut-tanned leather is compact, firm, flexible and waterproof, with a warm colour. It resists traction and abrasion and holds up to light. Because chestnut tannin tends to give a brownish tone, tanners usually combine it with quebracho, mimosa, tara, myrabolans and valonia. The wood seems to reach its highest tannin content after the tree turns 30 years old. Southern European chestnut wood usually holds at least 10 to 13 percent more tannin than that of northern climates.

  Other uses range widely. Chestnut meal can starch fabric and whiten linen, and the leaves and the skins of the fruit make a hair shampoo. Hydrolysable chestnut tannins can partly replace phenol in phenolic resin adhesives.

  The Sacred Chestnut of Istán, in Spain, measures 13.5 metres around and is estimated to be between 800 and 1,000 years old.

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