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Banana fruit and tree

The banana is so popular in Uganda that the locals eat about 250 kg each per year. In fact, the banana is so essential to their diet, that their word "matooke" means both "food" and "banana". The banana is not quite as popular elsewhere, but kids around the world like it because it's tasty, and because it's so easy to peel and devour. And they believe two things about bananas that are wrong. First, that the yellow banana is not a fruit (because it has no seeds), and second, that it comes from a tree (the banana tree).

There are close to 1,000 species of banana today. Most of them are inedible - they carry hard pea-sized seeds, and have only a small amount of bad-tasting flesh. The botanists think that about 10,000 years ago, probably in South-East Asia, a random mutation produced a sterile banana with no seeds and lots of flesh that could be eaten uncooked. The internal dark lines and spots inside today's banana are the vestigial remnant of these seeds.

Bananas were taken to India, where Alexander The Great saw them, and where they appear in 2,500-year-old cave paintings. Traders took them from India to East Africa, then overland to West Africa. Portuguese sailors took them to the Canary Islands, from where they got to Haiti by the 15th century. They were imported into North America shortly after European settlement, and became freely available in American fruit markets by the 19th century.

Bananas first came to Australia by two separate pathways - one for the West coast, and one for the East coast.

They arrived in Western Australia in the early 1800s, when Chinese workers carried some plants with them to Carnarvon directly from China.

But bananas travelled to Queensland via a very convoluted pathway. In 1828, two banana plants were taken from Mauritius and hand-delivered to Lord Cavendish. He grew some bananas from them in what became the current Kew Gardens in the UK. Missionaries took some of his banana plants to the South Pacific in 1840, where they flourished. Later, a missionary called Williams took some of these bananas to Fiji. In the 1870s, Queensland sugar cane plantation owners "drafted" sugar cane cutters from Fiji, and brought back some banana plants with them. In 1891, Herman Reich used these plants to start the Coffs Harbour plantations, which, after a century or so, had gone bananas.

But the edible farmed banana has no seeds. So how do we get new bananas? They take cuttings from an existing banana plant.

New banana "trees" are "born" in a new location when the shoots of cuttings are planted in the ground, and take root successfully.

The cycle starts with an underground stem (or vigorous root), often metres across, that can have several banana "trees" growing from it. Each of these so-called "trees" started from an underground "bud".

A "bud" will push up a shoot, which breaks through the soil. The shoot is made of leaves, wrapped tightly around each other, so that it looks like a green tree trunk - even though there is no wood present. The oldest leaves are on the outside, with the newest leaves pushing upward through the middle.

When the time is right, the underground stem switches from making leaves, to making an "inflorescence", which makes flowers, and subsequently, fruit. The inflorescence has a broad leaf-like structure that wraps around a hand of flowers, which ultimately turn into a hand of bananas. The final "tree" can be up to 6 metres tall, with bunches of 50-150 individual fruits or "fingers" of bananas, broken up into hands of 10-20 bananas each.

Once that particular underground bud has grown an inflorescence, it cannot reset itself to growing leaves, and ultimately, another "trunk". It has done its dash. So that bud and trunk will die and wither away. But in the next summer, other buds appear on the underground stem, and so the cycle continues.

So bananas are definitely a fruit, even though the fruit is sterile and has no seeds.

And the banana hand does not grow on a tree. It grows on a plant. But it's not a tree, because it's made from leaves, not true woody tissue.

So even though the banana has a phallic shape, it is a sterile and mutant fruit that has not had sex for 10,000 years.

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