Bananas and plantains (Musa spp.)
MUSACEAE, Banana Family
Bananas and plantains (Musa) have played interesting and important roles in the history of human civilizations. These seedless fruits are eaten and joked about by Westerners, but they also constitute a crucial part of human diets in all tropical regions. In the same plot of land where one could harvest 98 pounds of white potatoes or 33 pounds of wheat, a person could also harvest 4400 pounds of bananas with very little labor. Bananas are very rich in carbohydrates, vitamin C (also A and some B vitamins), and several important minerals, including potassium, copper, magnesium, calcium, and iron. In Uganda, working males consume 5 pounds of banana pulp per head per day, which is equal to about 3600 calories. In comparison with white potatoes, bananas have the same amount of caloric value but less fat and almost no protein. Annual world production of Musa fruit exceeds 40 million metric tons.
Around the world, there are more than 100 common names used for the fruits of Musa. The word "banana" originated in coastal West Africa, presumably in Guinea or Sierra Leone, and was adopted in the New World for the sweet forms with yellow skin (peel). The word plantain (accent either syllable) is now widely used to refer to the starchy cooking bananas, which often have green or red skins. Plantain presumably originated from the Spanish word plantano. The sweet banana is very easily digested, but the plantain must be boiled, steamed, roasted, or deep fried to make it soft and palatable.
Linnaeus created the name Musa, which is similar to several Arabic words for the fruit, but the name may also be linked to Antonius Musa, a Roman medical man of the first century B.C., or to honor the Muses. The Koran called this the "Tree of Paradise," so Linnaeus named one form Musa paradisiaca, and Pliny the Elder noted how the sages in India ate this fruit, "the plant of the wise," hence the other Linnean name Musa sapientum.
The banana "tree" grows in humid lowland to upland tropical areas; these plants die if they are exposed to cold temperatures. This is not really a tree but an arborescent (tree-like) perennial herb, which grows in the humid tropics like a grass, becoming a tree within a year. A false stem, the pseudostem, is formed by the bases of the leaves. The shoot apex is not found at the top of the plant but instead is present at ground level. When the shoot is mature, the shoot apex forms into a flowering structure that grows upward through the pseudostem and emerges at the top as a gigantic inflorescence. Consequently, when flowering and fruit production are completed, that shoot dies, because the apex has been used up. However, new offsets are formed at the base of the plant on the corm. Thus, a commercial plant is a system that can be productive up to ten years, and the corm or suckers are cut off and used to start new plants by vegetative propagation. Vegetative propagation is essential because the plants never form seeds.
Banana is a monoecious plant. Its inflorescence has male flowers at the tip, several sterile flowers, and female flowers behind. For wild bananas, birds usually pollinate the female flowers, but pollination is unnecessary for fruit set of the cultivated forms, which form sterile fruits automatically without the presence of pollen. This type of fruit development is called parthenocarpy. The ovules that were present in the ovary abort their development, and the pulp subsequently is produced by the enlargement of the internal tissues of the ovary, particularly from the inner face of the skin and the enlargement of the septa and central axis. These cell divisions are stimulated by the presence of high levels of auxin in those tissues, which are not present if the ovules are fertilized. Wild bananas have fairly dry fruits with large seeds and no pulp.
The fruit of a banana or plantain is a berry with a leathery outer peel that contains much collenchyma. An unripened banana and the plantain have high starch and low sugar levels plus copious amounts of bitter-tasting latex. Starch is converted to sugar as the fruit ripens, so that bananas can eventually have about 25% sugar. As the banana ripens, the latex is also broken down. Plantain has the stinging, bitter latex, so the peel is removed with a knife and the pulp is soaked in salt water for 5-10 minutes before cooking.
The fruits ("fingers") are formed in layers called combs or hands, consisting of 10-20 bananas, and there are 6-15 combs per stalk, which equals 40-50 kilograms per stalk or ten or more tons per acre per year. A large plantation can yield more than 20 tons of bananas every week. The fruiting stalk is often covered with plastic as it ripens to keep away insects and fruit-eating birds. In commercial operations, the large terminal bud and bracts are removed to redirect sugars to the developing fruits. When ready, the entire stalk is cut with a knife, sometimes attached to a long pole, lowered gently onto the shoulders of a worker, and transported quickly to the processing area, to avoid heating and bruising. Bananas are harvested unripe and green, because they can ripen and spoil very rapidly. Bananas are then cleaned of old floral parts, combs are divided into smaller bunches, poorly formed fruits are removed, and bunches are thrown into a water bath, where latex is washed away. Then fruits are dried and usually place in a ripening room for several days before going to market on Day 4, or exported after storing and packing with cushion (usually paper), where delivery to your store could be 15-20 days. Fruits that are eaten locally are much sweeter than shipped fruits. Presence of naturally formed ethylene gas, produced by ripen fruits, hastens the ripening of surrounding, greener fruits; you can use that knowledge to speed the yellowing of green fruits, and ethylene gas can be used commercially to cause green bananas to start ripening.
Typical parthenocarpic bananas and plantains belong to one "species," Musa X paradisiaca, which has more than 300 recognized forms and cultivars. This apparently is a hybrid between a pulpy-fruited form of M. acuminata, a diploid (AA), and M. balbisiana, a tetraploid (BBBB), which formed plants of mixed characteristics. Most plants are triploids (e.g., AAB or ABB; 3n=33); triploidy was probably the factor that made bananas seedless and pulpy. The presumed origin of the parthenocarpic and seedless condition of Musa X paradisiaca was in Malaya or the islands to the south of there, and other species of banana grow in Southeast Asia. Hybrids probably developed independently in eastern Malaysia and in India, and possibly elsewhere. In Malaysia, Indochina, India, and the Philippines, a great diversity of bananas can be found in the market places. The primitive seeded bananas are termed tae manu, meaning animals feces, which tells you that nowadays they are not eaten except during famine.
Before agriculture began in Southeast Asia, wild Musa was probably already being eaten. In fact, gatherers use the male flower buds and the inner sheath of the pseudostem for boiled foods. Researchers suspect that this plant may have been one of the first crop plants in Asia, to supplement a fish diet (protein). Unfortunately, early accounts of banana are absent. The oldest records of edible bananas come from India (600 B.C.), described in the Epics of the Pali Buddhist canon, and the 'Horn Plantain' was in existence in India at least since 350 B.C. The first Chinese record is 200 A.D. Experts suspect also that Musa was introduced to the East African uplands around 500 B.C. by Indonesian travelers, who probably also brought techniques of canoe building and musical instruments to such places as Uganda and Madagascar. Later, Arabs introduced other forms of banana to the lowlands of East Africa. Bananas were arrived in the Mediterranean region in 650 A.D. via the Mohammedan conquest.
Bananas and plantains have had a tremendous impact on tropical cultures over the last 1000 years. The Polynesians carried these eastward. At least one researcher has tried to trace the routes of Polynesian colonization by studying the banana forms in the Pacific Basin. The westward spread of Musa in central Africa is credited by some workers with the population expansion of the Bantu-speaking peoples and, thus, history of that part of the continent. Bananas from West Africa were planted by the Portuguese on the Canary Islands (by early 1500s), and from there to Santo Domingo in the West Indies (1516).
Bananas were rarely seen in the United States before 1880. These fruits are perishable and therefore require cool temperatures (57 degrees F) to keep. Hence, they could only be shipped to temperate regions in refrigerated ships, which only appeared in 1880. Only those bananas that were most durable were shipped, and even today the best tropical bananas cannot be shipped to the U.S. and are therefore unappreciated by us. The banana became a focal point for development of Central America, the so-called "banana republics," when the United Fruit Company, formed in 1899, began to develop a system of transportation to bring shipments of fresh bananas to U.S. markets, thereby controlling the destinies of those countries, heavily controlled by wealthy landowners and the large fruit growers. Consequently, much of the upheaval in Central America, and the need for agrarian reform, can be traced back to bananas, which found their way to U.S. cereal dishes and fruit bowls in 1929. Ironically, then the seed of much hatred by Central America for U.S. policies developed from the seedless banana.
Among the edible bananas, the only important diploid of M. acuminatais 'Sucrier'. This fruit is sweet and thin-skinned. The major triploid bananas that are shipped are 'Gros Michel' or cultivars derived from "Cavendish" stock. In Central America, 'Gros Michel' and 'Poyo' Cavendish were wiped out virtually overnight by Panama disease, a fungus (Fusarium oxysporium cubense), which attacks the phloem. Fortunately, some banana clones showed resistance in the field, and growers reestablished plantations with those plants. Now the Jamaican clone 'Valery' (a robust Cavendish banana) is what is grown widely in Central America, because it is resistant to Panama disease.
An interesting plant is the Fe'i banana (M. fehi), which is a specialty food on Tahiti. This species is noteworthy because the inflorescence is erect, not pendent, as in typical forms.
Another important economic member of this family is Musa textilis, the source of Manila hemp or abacá. The banana family includes two genera, Musa (35 spp.) and Ensete (7 spp.). Other close relatives of the Musaceae, with banana-like leaves are the Heliconiaceae (Heliconia, at least125 spp.; lobster-claw) from the American tropics, and Strelitziaceae from the African tropics. Strelitzia includes the bird-of-paradise flower, which is widely cultivated in California, as well as the traveler palm of the tropics, Ravenala madagascariensis, whose leaf bases can be a source of fresh water.