One banana, two banana, three banana more

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The popular press often delights in informing us that the bureaucrats of the European Union wish to regulate for a straight banana. In the truth behind such stories lies the irony that is the banana. It is certainly the case that the bananas to be found on most of the supermarket shelves of Europe vary in little more than price. In absolute contrast the bananas and plantains cultivated throughout the tropics are so wonderfully variable that the species concept is unable to cope, and attempts to ascribe a Latin name are a futile nonsense.

The name banana is loosely applied to cover several true species as well as a complex set of hybrids between them. Generally the term banana is used to refer to plants grown to be eaten raw, while the term plantain describes a larger and more angular fruit which is eaten cooked. However, bananas can be cooked and plantains can be eaten raw and the two terms can be locally interchangeable. Additionally plants have been cultivated not only for their fruit, but also for their fibres, leaves, stems and sap, or just for ornament and for the shade they provide for other plants.

The majority of edible bananas and plantains are descended from just two wild species; Musa acuminata and Musa balbisiana, unfortunately neither of these really have common names. The first bananas to be cultivated were probably plants of Musa acuminata growing in the humid forests of Malaysia. In the wild most of these plants produce fruits full of large seeds, but if unpollinated (and pollination is usually by bats) some plants develop fruit without seeds. Mankind, by choosing plants that are female sterile which do not produce seeds even but yet still develop fruit, created the first edible bananas. Banana cultivation then spread north into the seasonally drier monsoon areas, where it came into contact with Musa balbisiana and because very occasionally bananas can produce seeds these two species were able to hybridise for the first time.

Most animal species contain just two sets of chromosomes (one from either parent) and are referred to as diploids. Plants, however, tend to be more tolerant of extra copies, this is particularly true of bananas. The outcome of what must have been the promiscuous sexual activity between the descendants of Musa acuminata and Musa balbisiana has been to produce plants with a whole array of chromosome combinations. If we use the letter A to represent a set of chromosomes from Musa acuminata and B for a set from Musa balbisiana, then the plants currently in cultivation include: AA, AB, AAA, AAB, and ABB.  Plants with higher numbers of chromosomes such as AAAA, AAAB, AABB, and ABBB also frequently occur. Generally speaking, fruit commonly thought of as bananas contain only sets of A’s while plants considered as plantains contain at least one set of B’s. Plants with few sets of chromosomes tend to produce smaller, thinner-skinned fruit than those with multiple chromosomes. Within this vast cloud of variation, which defines most bananas, lie: fat ones and thin ones, straight ones and bent ones, sweet ones and starchy ones, red ones and green ones. And also something you would recognise on your supermarket shelf.

Meanwhile outside this complex swarm of hybrid bananas, lie three further species of cultivated banana. The Manila hemp from the Philippians, which, as its name suggests, is grown for its fibres. It has been used in the manufacture of strong ropes and also for less strong tea bags. The Abyssinian banana from the highlands of Ethiopia is also grown for fibre, but additionally its starchy stems are regularly eaten. The cultivation of both these species is thought to be ancient but it is uncertain, with no direct evidence, that they were originally cultivated in the areas in which they now occur. Finally the Polynesian Fehi bananas with their copper coloured thick-skinned fruit have been cultivated, not only because they are good to eat either roasted or boiled, but also for their sap, which yields a red ink.

The harvesting of bananas can be a messy business since the sap of all bananas cause indelible stains on clothes. Even so humans have used them in many different ways. In Central America, the sap of red bananas is collected as an aphrodisiac, by cutting the stems close to the ground and hollowing out the top of the stump. It is perhaps surprising that the banana does not have more such sexual associations. Hindus are said to regard the plant as a fertility symbol. However and perhaps naively, this has been attributed to the fact that the plant fruits throughout the year.

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