Temperate Fruit

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Temperate Fruit

Many of the world's best-known and favorite fruits (such as apple, pear, peach, plum, grape, and strawberry) are adapted to climates in the middle latitudes and are known as temperate fruits. Temperate fruits have two climatic adaptations: they require some cold periods (dormancy) to complete their life cycle, which conditions their adaptation in tropical climates, and they have various degrees of winter hardiness, which conditions their adaptability in cold climates. Fruits that do not specifically require cold but have slight frost tolerance (citrus, fig, olive, persimmon, pomegranate) are known as subtropical fruits; they are not discussed here. In contrast, tropical fruits typically are very sensitive to cold and are often injured by low temperatures above freezing. Temperate fruits are usually classified by their growth habit as tree fruits (apple, pear, peach), vine fruits (grape, kiwifruit), or small fruits (strawberry, raspberry, currant, and blueberry). The term "small fruits" refers to the size of the plant and not necessarily the fruit. In the United Kingdom they are better known as bush fruits or soft fruits.

Tree Fruits

The best-known temperate tree fruits are members of the rose family (Rosaceae). These include the pome and stone fruits. Pome fruits (apple, pear, quince, and medlar) are fleshy fruits in which the outer portion is formed by expanded floral parts and receptacle. The stone fruits, all members of the genus Prunus (almond, apricot, cherry, peach, nectarine, and plum) are fleshy fruits that contain a stony pit (hence the name "stone fruits"), which encloses a solitary seed.

Apple (Malus × domestica ) is the best known of the pome fruits. It has been known since antiquity and is grown in Siberia and northern China where winter temperatures can fall as low as –40°F and in high elevations in Colombia as well as Java, Indonesia, straddling the equator, where two crops can be produced in a single year provided leaves are stripped. While there are many species of Malus, the domesticated kinds seem to be derived from M. siversii indigenous to Kazakhstan and neighboring countries where forests of wild apple contain seedlings with all of the characteristics of the domesticated sorts. Apples are popular because they can be consumed in many ways: fresh, dried, or cooked and in liquid form as juice, alcoholic cider, or brandy (Calvados). Processed apples are appreciated as a filling for many bakery items and enjoyed as a sauce or concentrated as a butter. Some apples have a long storage life under refrigeration, in some cases as long as a year, especially under controlled atmospheres (low oxygen). In the United States the apple is the symbol of wholesomeness; "an apple a day keeps the doctor away" is a popular aphorism.

Pear (Pyrus species) can be divided into two types, the European pear (P. communis ), which usually are consumed when they soften after harvest, and the Asian pear (P. pyrifolia and P. ussuriensis ), which are consumed when crisp. The pear is as old a fruit crop as apple but is somewhat less popular in the West. This is probably because the postharvest ripening required makes it difficult to determine optimum quality, and some fruits contain grit (stone cells), which can be objectionable. Asian pears (known as nashi in Japan and as li in China) are probably more popular than apples in China, Japan, and Korea. Pears are closely related to apples and are consumed in similar ways.

The quince (Cydonia oblonga ) is the third most important pome fruit. It is not very popular because most are too sour and astringent to be consumed raw, but it is excellent cooked, especially in preserves, jams, and jellies, to which sugar is added. Some types grown in warm climates soften and can be consumed raw. It is an important crop in Argentina. Some quinces are used as dwarfing rootstocks for pear. Quinces have a wonderful perfume and should be more widely grown but have passed into the realm of a neglected fruit. The Asian quinces (species of Chaenomeles ) are often grown as ornamentals, but there have been attempts to domesticate these species in the Balkans for juices and preserves.

Medlar (Mespilus germanica ) is truly an almost forgotten fruit. It is mentioned and disparaged by Shakespeare, who notes that it must be almost rotten to be enjoyed. The medlar is inedible until an internal fermentation occurs, producing an aromatic taste that appeals to some. The medlar can still be found in Italian markets.

The peach, despite its scientific name (Prunus persica ), which suggests a Persian origin, is native to China, where it has always been highly prized for the beauty of its flowers and fruit. The peach seems to have been introduced to Europe via Persia in the first century b.c.e. but may have been known to the Greek philosopher Theophrastus (372–287 b.c.e.), who writes of Persian fruit and Persian apple. The fruit was well known to the Romans, and pictures of peaches were found in Herculaneum, destroyed in the eruption of Vesuvius in 79 C.E. Peach germplasm was introduced to the United States by the Spanish in the sixteenth century and became naturalized, but quality was low. Introductions from China in the middle of the nineteenth century, particularly one called Chinese Cling, are the progenitors of modern American cultivars. Peach is now the most popular temperate summer fruit. There are a number of distinct types. The freestone types with melting flesh and white or yellow flesh are usually consumed fresh. The cling-stone, rubbery-flesh types are used in processing. The nectarine, a peach with a nonfuzzy skin, resulted from a mutation. Peentao, a saucer-shaped, flat peach is another variant type. Breeding in the United States has created many cultivars of both peach and nectarine that are widely grown in Europe, and some have been reintroduced to China for greenhouse production.

Almond (Prunus amygdalus ) is native to the hot arid regions of western Asia but was introduced to Greece and West Africa in prehistory. The flesh is leathery and inedible, although the very immature fruits are consumed in Arab countries. Unlike most stone fruits, which have a bitter seed due to hydrocyanic (prussic) acid, the seeds of almond are nonbitter and are the edible part of this fruit. This species is therefore discussed under nuts. The almond is the most extensively planted "fruit" in California and is widely grown in countries of the Mediterranean basin.

Cherries, one of the most popular early summer fruits, are a symbol of joy as expressed in a famous song line: "life is just a bowl of cherries." There are about thirty species of cherry. The edible types include sweet cherry (Prunus aviuim ), a diploid with two sets of chromosomes (2n = 16), and tart (sour) cherry (P. cerasus ), a tetraploid with four sets of chromosomes (2n = 32). Another tetraploid type called Duke cherry is derived from a hybrid between sweet and tart cherries. Cherries may be red, yellow, or bicolored and are consumed fresh, dried, or processed, including as a liquor called kirsch. The Maraschino cherry is almost an artificial fruit in which cherries are brined, bleached, and then artificially colored and flavored with bitter almond oil. They are often used in a wonderful confection: chocolate-covered cherries. Cherries are now available over a long season in North American markets due to the efforts of American and Canadian breeders.

Apricot (Prunus armeniaca ), an ancient fruit native to central Asia and China, was thought by the Greeks to have originated in Armenia, hence its scientific name. The beautiful, aromatic fruit with a velvety skin is consumed fresh, dried, and processed. Apricot liquor is well appreciated. The apricot blooms very early, is subject to spring frost, and is difficult to grow. This may explain why apricot has not become as important as peach, cherry, or plum. The beautifully flowered Chinese plum (P. mume ) is more properly included with the apricots than the plums.

Plums are a diverse group of fruits, as exemplified by the many names by which they are known: bullaces, cherry plums, damsons, date plums, egg plums, greengages, mirabelles, plums, prunes, and sloes. Various species originated in Europe, Asia, and America. Two European species (Prunus domestica and P. insititia ) are hexaploid, with six sets of chromosomes. The domestica plums include several groups of cultivars, such as greengage and prune types, while P. insititia includes bullaces, damsons, mirabelles, and St. Julien types. Among Asiatic species are P. salicina and P. simonii, the former of which includes both red-and green-fleshed Japanese plums. Many of these were introduced by Luther Burbank, with the red-fleshed Santa Rosa being the best known. P. simonii (apricot plum) is cultivated in China. There are a number of American plum species, but none are widely cultivated. At the start of the twenty-first century, the world plum industry is largely made up of P. domestica in Europe and P. salicina in Asia. Plums are consumed fresh or dried. Plums that dry without fermentation are called prune plums or simply prunes. They are dried down to very low moisture levels, in which state they can be stored for long periods of time. They are rehydrated when they are sold as packaged prunes, processed into jelly and jam (popular as a bakery filling), made into a diluted juice, or turned into brandy or cordials. The wrinkled dried fruit was widely consumed by senior citizens because of its laxative properties and thus became a source of comic derision. (It has been said that the turndown service at senior hostels includes a prune rather than a chocolate on the bed.) As a result, the industry has changed the name of prune to dried plum!

Vine Fruits

Grapes (species of Vitis, Vitaceae, or grape, family), one of the most important temperate fruit species, are usually grown on trellises. Total world production of this fruit is surpassed only by all citrus and species of Musa (banana and plantain). Grapes derived from the European species, V. vinifera, have been prized as the source of wine since antiquity. Although wine can be made from any sweet fruit, the grape is the preferred species because the combination of sugars, acids, and astringent substances such as tannins gives character to the product. The name of wines, such as cabernet sauvignon and pinot noir, refer to the grape cultivar. Because these wines have become a standard product there is great reluctance to change grape cultivars used for wine, but various clones have been selected throughout the many years they have been cultivated. Some grapes (known as table grapes) can also be enjoyed fresh; many of the new cultivars bred for this purpose are seedless. Nonalcoholic grape juice is enjoyed in the United States; this industry derives from Concord, a cultivar of the American species V. labrusca, the fox grape. American grapes are typically winter-hardy and have a slip skin and a unique flavor referred to as foxy. Concord juice in the United States is also used to make the sweet wine used traditionally in Jewish ceremonies, a product often derided by wine connoisseurs but still enjoyed by millions of ordinary folk. (When the astronaut Gene Cernan landed on the moon, he expressed his wonder at the sight with the famous expression "Man O Manischewitz," the name of a popular brand!) American grapes have long been grown in Japan, where their foxy flavor is appreciated. The large-fruited table grape Italia, widely appreciated in Europe, has a muscat flavor that is similar to the foxy flavor of labrusca grapes, many of which are sweet and pleasant but insipid. The strong-flavored muscadine (V. rotundifolia ), native to the southern United States, has a small market in this area for fresh fruit, juice, and wine.

The kiwifruit (Actinidia deliciosa, Actinidiaceae) is an example of a fruit species that has been essentially domesticated in the twentieth century. It derives from a gathered Chinese fruit known as yangtao, which had long been appreciated in China but was collected rather than cultivated. Introduced to the United States and New Zealand early in the twentieth century by the plant explorer E. H. (Chinese) Wilson, it was referred to as Chinese gooseberries. Although it remained a curiosity in the United States, New Zealand growers and nurserymen succeeded in domesticating the crop by selecting suitable male and female clones (the plant is dioecious), as well as techniques for cultivation. One seedling selected by A. Hayward Wright and subsequently named Hayward became the mainstay of the world industry. The fruit was exported to the United States and promoted by Frieda Caplan, a marketer of new crops. In 1959 the relatively unattractive brown fruit received the new name kiwifruit after the kiwi, an endemic flightless bird often used as a nickname for New Zealanders. Kiwifruit has a pleasant but weak flavor with very high vitamin C content, but the nutritious quality of the fruit has not been promoted; rather, it was the beautiful and unique appearance of the sliced flesh, which is used as a garnish on bakery products or as a component of mixed fruit, that made this fruit popular worldwide. The long storage life of the fruit made it possible for New Zealand to export the fruit year-round. The popularity of the crop made millionaires of many New Zealand growers, but as kiwifruit began to be grown in such countries as the United States, Italy, and Chile, the boom crashed and New Zealand growers had to struggle to survive. Kiwifruit is consumed out of hand in New Zealand, usually scooped with a spoon, but this technique has not caught on, and further expansion is probably linked to development of a simple method for peeling. A yellow-fleshed kiwifruit marketed as Zespri Gold (A. chinensis ) was introduced at the turn of the twenty-first century, and the New Zealand growers are attempting to control its distribution. It is too early to know if this will succeed. A small-fruited hardy American species (A. arguta ), sometimes called tara fig, is now cultivated in gardens but this species has not been commercialized.

Small Fruits

Strawberry, the most widely grown small fruit, has an interesting history. Although a small-fruited species of strawberry (Fragaria vesca, a diploid species, 2n = 16) is native to Europe, the modern strawberry is derived from hybrids between two octoploid (2n = 56) native American species, F. virginiana, indigenous to the East Coast of North America, and F. chiloensis, native to Chile. Hybrids between these two species were produced naturally in Brest, France, early in the eighteenth century when a pistillate clone of the large-fruited F. chiloensis, introduced by Amedée François Frezier, a French army officer, was interplanted with staminate plants of F. virginiana. The new hybrids (now known as Fragaria × ananassa, or pineapple-strawberry) initiated the modern strawberry industry. Breeding efforts through the years have resulted in tremendous advances as the plant was changed from a predominantly dioecious species with male and female plants to a hermaphroditic species, in which flowers contain both stamens and pistils. Fruit size has been greatly increased, and modern cultivars tend to be very firm-fleshed (too firm for some), with improved flavor and appearance. Although strawberries are grown in all temperate countries, the industry is now concentrated in some favored locations such as southern California in the United States, southern Spain, and various locations in Italy. Some strawberries now are grown in greenhouses.

The genus Rubus is very diverse. The cultivated Rubus species known as brambles includes red raspberry (R. idaeus ), black raspberry (R. occidentalis ), and blackberry (Rubus species ), including various interspecific hybrids between raspberry and blackberry, such as loganberry, boysenberry, and tayberry. Brambles have delicious flavors but marketing has been a problem because of the soft texture of the fruit.

Cultivated species of Vaccinium and Ericaceae are berry crops domesticated in the twentieth century. Blueberry (various species) is native to the United States and grows in bushes of various heights. The blue fruits are easy to preserve by freezing and have become very popular in the United States because of their use as a fresh fruit and in muffins or pancakes. They are increasing in popularity in Europe and in New Zealand. The cranberry (V. macrocarpon ) is an unusual berry crop because it is grown submerged in bogs. The fruits are too acid to be eaten raw and are consumed processed as jelly or as a sauce. In the United States cranberry is a favorite food for the feast of Thanksgiving. Sweetened dilute cranberry juice, consumed alone or mixed with other fruit juices, has become popular because of its therapeutic benefits in urinary tract problems of women. Lingonberry (V. vitisidaea minus ) is native to northern regions of Europe, Asia, and North America. The bright red fruit has long been gathered from wild stands in Scandinavia, and a large commerce developed from this source. Attempts to domesticate the crop are based on the management of natural stands. There are a number of other native Vacciniums, such as bilberry (V. myrtillus ) and bog bilberry (V. uliginosum ), that have been considered as possible domesticates.

Cultivated Ribes species include a number of popular berries such as black currant (Ribes nigrum ), red and white currant (R. sativum and R. rubrum ), and gooseberries (R. grossularia ). They are too acid to be consumed fresh and are essentially used for jams, jellies, and juice. Black currant was the source of ribena syrup, widely fed to British children during World War II as a source of vitamins. Black currant is not widely grown in North America because cultivation was discouraged and even made illegal because the plants were alternate hosts for white pine blister rust.

See also Apple; Berries; Grapes and Grape Juice; Wine; Wine in the Modern World.