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Lost Crops of Africa: Fruits, Volume III
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Lost Crops of Africa: Fruits, Volume III 14 TREE GRAPES About 40 different trees belonging to the genus Lannea are about equally divided between the tropics of Asia and Africa. The Asian species have received some horticultural assessment, but the practical literature tells little about the score or more native between Madagascar and Senegal. Yet out of these African species perhaps a dozen merit consideration as future food resources. Wherever they occur their fruits are avidly eaten; some already play a part in commerce. In West Africa, for instance, people commonly sell them both in city markets and along rural roadsides—a feature to be witnessed in and around Ouagadougou, for example. Although Lannea belongs to the Anacardiaceae, the same family as mango, cashew, and pistachio, the fruits are more like grapes. They come in pendulous bunches and are reddish, purple, or black, with a whitish bloom on the skin. Although some have a resinous taste, many have a pleasant flavor commonly described as “grape-like.” In other ways, however, lannea fruits differ greatly from grapes. They are borne on trees, not vines. Most are much smaller than today’s cultivated grape—being about 1 cm long at full ripeness. Each is capped at one end with three or four little “horns,” the remains of the flower’s styles. And inside, one finds a central stone. Indeed, botanically speaking, they are more like plums than grapes, and are classified as drupes, not berries. The trees themselves seem conducive to cultivation. They are resilient, tolerant of drought, and often occur naturally in harsh sites, including some in which the human inhabitants have few food options.1 They resist burning; the ground fires that are so prevalent and so destructive in the savannas leave them undamaged. The flowers attract bees in such numbers that beekeepers fight to hang their hives amid the branches. Like the grape of international commerce, African tree grapes have multiple uses. They make a very good jam. Their juice is fermented into 1 In parts of the Horn of Africa, the roots of some Lannea species (mostly Lannea triphylla) are often considered more important as food than the fruits. After the rains come, but before anything has grown to eat, these Lannea roots swell to become juicy and tasty. Digging the roots can destroy the tree but save lives, and some efforts have begun to turn this desperation food into a sustainable resource.
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Lost Crops of Africa: Fruits, Volume III Tree Grapes. Although in the same plant family as mango, cashew, and pistachio, tree-grape fruits show their grape-like form. They also hang in bunches like grapes. And when ripe they are reddish to purplish-black skins with a whitish bloom. Perhaps most intriguing, many have a pleasant flavor described as truly “grape-like.” These are thought to be Lannea microcarpa, photographed at Malamawa Jibrim, 13 km southwest of Zinder, Niger. (Josef Garvi, Eden Foundation) “wine.” They can be dried like raisins and safely put aside for later use. And those “tree raisins” themselves can be fermented into a beverage—an often-all-too-potent beverage. Even when the fruits are unwanted, these trees are useful. They coppice well and sprout with vigor if the branches are cut at the proper time of year. This makes them useful for live hedges. The bark yields a water-soluble edible gum and a reddish-brown dye, as well as a fiber used among other things for cordage. The living trees also provide poles and floats for fishing. Oil from the seed kernel is used for soap and unguents. These versatile wild resources are well worth exploratory research. Tree grapes are plants that could especially reward adventurous botanists, horticulturalists, and ethnologists. For plant physiologists and pathologists they present some fascinating mysteries. For horticulturists, their selection and growth requirements are complex enough to challenge the best minds. And anyone succeeding in overcoming these plants’ problems will reap the satisfaction of having created crops capable of contributing to the health and wealth of some of the world’s most destitute corners.
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Lost Crops of Africa: Fruits, Volume III Whether any of these species have a future in substantial cultivation, or even in enhanced production in the wild, is unclear. Finding out is important. One first step might be the documentation of traditional usages. As the plants are already widely known, information on the various local ways of using it will enable an assessment of their continent-wide potential. Nutrition research and consumer trials could complement this local-uses information. After the plants’ baseline information becomes better known, the practical research and development activities can be undertaken with more confidence. Also, it will then become easier to carry out awareness campaigns leading to greater popularity, improved production, and perhaps new profit in terms of subsistence and income. Certainly, it will not be easy to advance these resources. Tree grapes are notoriously difficult to propagate vegetatively.2 This poses a problem because plants grown from seed take years before they start flowering, and growers must wait an inordinate time before learning whether an individual tree is male, female, hermaphrodite, or hermaphrodite-but-functionally-female, and whether the fruit is worth eating. The adventurous souls who address such challenges typically plant groups of seeds, and then later rogue out all of the unwanted types. This is wasteful of time, effort, and money, and is unlikely to ever be widely adopted in everyday practice. One advance that would make everything else more successful is the selection of types that provide the best eating. Such genetic selection yet awaits the dedicated, observant, and practical pioneers. Following are brief descriptions of the best-known species. Lannea edulis (Sond.) Engl. The “wild grape” of the southern half of tropical Africa3 is a common and well-liked fruit that grows on what has been called an “underground” tree. The mass of this amazing plant is mostly buried out of sight beneath the soil. The subterranean trunks, often as thick as fenceposts (13 cm in diameter), creep along just beneath the surface. The branchlets bearing the leaves, flowers, and fruits stick up only slightly (3-30 cm) above ground. The whole tree nonetheless can be very big. A single specimen may cover many square meters, but disguised in the dirt, its massive size is seldom realized. In addition to its self-burying trunks, a deeply penetrating root system anchors the tree and endows it exceptional survivability under drought stress. Moreover, this is not the only unusual botanical feature of this strange species. At the end of the dry season, bunches of small flowers pop out 2 Information from J.D. Carr. 3 It is known, for example, in South Africa, Botswana, Namibia, Zimbabwe, Zambia, Malawi, Angola, and Congo. In Zambia and Zimbabwe, it is a common shrub of woodland and vlei margins on the high veld. The trees are often so inconspicuous as to be noticeable only in land cleared for cultivation.
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Lost Crops of Africa: Fruits, Volume III directly from the leafless stems, each bunch hanging from the bare wood and looking for all the world like creamy-yellow tinsel sprinkled over the land. People like these almost magical flowers, which are harbingers of the rains and of the better times soon to arrive.4 Later, the fruits begin forming. Eventually, they hang in grape-like bunches almost touching the ground, ripening slowly from pink through scarlet to wine-red and eventually black. Inside their thin skin is found smooth green flesh and a bean-shaped stone. In most the layer of pulp is thin, but whatever there is normally is juicy and pleasantly sour. They are exceptionally popular, particularly with children. Throughout much of southern Africa, kids squeezing tree grapes between their fingers and shooting the pulp into their mouths is a common sight. Lannea discolor (Sond.) Engl. The plant known as “live-long” is also from the southern regions, but it grows in the normal fashion above ground. It is common in open grassland, bush, and woodland from Swaziland and South Africa (Gauteng) to northern Namibia, Mozambique, Botswana, Zambia, Zimbabwe, and Congo. It is deciduous and grows above ground, reaching 15 m in height. It is one of the first trees to drop its leaves as the rainy season winds down. Interestingly, this is one of the few plants of any kind that are established by planting branches.5 The ends of even large limbs are jabbed into the soil, where they strike new roots and flourish. In this manner, people get living fenceposts—hence the name “live-long.” Several cultures revere these trees, believing them to be favorite haunts of ancestral spirits.6 The fruit is reddish to purple, and merely the size of a pea. It has a pleasant grape-like flavor, and is popular. At least in Zimbabwe, the plants flower in spring and normally fruit before the onset of the main rains.7 Lannea microcarpa Engl. This tree grape of western Africa is enjoyed for both its fresh fruits and dried “raisins.” In either form, it is mostly boiled up into a sweet beverage. Particular types (sometimes designated as a separate species, Lannea oleosa) are apparently raised as a fully domesticated fruit crop in certain parts of West Africa. Indeed, this resource is even now of 4 Although the flowers normally come before the rains and the leaves after, it is not unusual for both to appear together. 5 This process of planting large woody cuttings may be more practical than professionals have assumed. Today, with the availability of rooting hormones and a desperate need for trees, the possibility of planting branches deserves a thorough exploration. Not only would it create “instant forests,” but it might circumvent hazards that take out tree seedlings, and thereby dramatically raise reforestation’s success rate (now miserably low in all too many locations). 6 Swazis call it “the tree of forgetfulness,” believing it to harbor benevolent spirits who reconcile any enemies that meet in its shade. 7 Information from Ray Perry.
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Lost Crops of Africa: Fruits, Volume III commercial importance. It is widely consumed in Burkina Faso, for example, and the tree is often seen cultivated in and around villages. It grows to 15 m tall, and because of the shade and tasty bounty it is typically protected when farmers clear wood from future cropland. And there are other useful products as well. The seed comprises a thin shell surrounding a kernel, whose copious oil is sometimes used to make soap or skincare products. The young leaves are edible and nutritious, containing 18 percent protein and 5 percent minerals. Cattle as well as passing humans commonly “browse” the foliage. Also, an edible (and soluble) gum exudes when the trunk is damaged. Lannea acida A. Rich. Notably common from Senegal to Niger and Benin, this West African tree grape is found as far to the east as Cameroon and the Central African Republic.8 A tall tree (up to 18 m), it occurs chiefly in the untouched bush far from villages. Its berry-like fruits (about 1 cm across and 1.5 cm long) occur in large clusters. Red to purple in color, they are popular and are consumed either fresh or dried. In dried form they look like currants and can be stored for use months later. To the tastebuds, the fresh fruits are slightly acidic and somewhat resinous. Both fresh and dried types are widely eaten and both are also fermented into drinks reminiscent of apple cider. The tree has only a brief fruiting period, but this coincides with the months when other foods—especially nutritious foods—are scarce. The young leaves are also edible, and they develop even before the rainy season begins. Both features help allay vital food-security fears. The plant tolerates dry soils but apparently requires either moist sites or annual precipitation of at least 600 mm to yield fruits well. It has above-average fire resistance, a critical feature in savannas where summer ground fires devastate any sensitive species. Although not cultivated on an organized basis, this tree grape can be deliberately planted and it grows well under human care. Prior to planting the seeds need a good soaking in warm water. A 2-minute acid bath, followed by washing and soaking 12 hours in water, is also recommended.9 The seeds then germinate well in soil-filled plastic bags. In the nursery, protection against rodents is necessary. The plant is dioecious, so to produce fruits a few males must be interspersed among many females. 8 It is called variously npekuni (Bambara), bembo (Mandinka), peguhi, bembey (Fula), sabaga, sabgha (More), and sonn (Wolof). 9 Bellefontaine, R. 1995. Synthèse des espèces des domaines sahélien et soudanien qui se multiplient naturellement par voie végétative. Pp. 95-104 in d'Herbès, J.M., J.M.K. Ambouta, and R. Peltier, eds, Actes de l'Atelier “Fonctionnement et gestion des écosystèmes forestiers contractés sahélien”, Niamey, Nov. 1995. ORSTOM - CIRAD - Ministère de l' Agriculture, Niamey.
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Lost Crops of Africa: Fruits, Volume III Whether other African tree grapes have any merits is uncertain. Among those recommended to us are the following. Lannea grandis. (Dennst.) Engl. West Africa. Shrub of the forested savannas. Lannea alata Engl. Tropical Africa. Fruits are edible. “Wool” stripped out of the root bark is used for padding and for stuffing mattresses. Lannea fulva (Engl.) Engl. Shrub and tree to 20m tall. Lannea gossweileri Exell & Mendonça Tropical Africa, including Zambia, Congo (Katanga), Angola, and Namibia. Lannea kerstingii Engl. & K. Krause Tropical Africa. Lannea velutina A. Rich. Western tropical Africa (Senegal to Ghana). Shrub or tree to 15 m. Fruit edible, foliage browsed. Lannea welwitschii (Hiern) Engl. West and Central Africa (Côte d’Ivoire to Uganda, as well Congo and Angola). Abundant in Cameroonian forests. The tree reaches 30 m. tall. Its small fruits (6-7 mm long) are blackish, viscous, and smell somewhat of turpentine. Regardless of that, they are widely eaten.
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