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Coco de Mer: Producer of the World’s Largest Seed

History and Legends of the World’s Largest Seed

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J.W.Alker / Getty Images

The world’s largest seed comes from the coco de mer (Lodoicea maldivica). Other common names used are Seychelles Island Palm, coco fesse, Maldive coconut, love nut, Seychelles nut, sea coconut, and double coconut. Not only is the coco de mer seed enormous but, because of its unique shape and size, it has a fascinating history.

About the Coco de Mer Tree

The coco de mer originates from the islands of Praslin and Curieuse in the Seychelles Islands. It was also found on the small islets of St Pierre, Chauve-Souris, and Ile Ronde (Round Island), all located near Praslin, but was extinct there for a time until recently reintroduced.

The coco de mer tree grows to 25 to 34 meters tall. The leaves are fan-shaped, 7 to 10 meters long and 4.5 meters wide. It is dioecious, meaning that reproduction requires separate male and female plants.

These plants grow wild on nutrient-starved, rocky soil. Nitrogen and phosphorus are two natural fertilizers with nutrients that these (and other plants) need. There isn’t much of either on the islands where these palms grow, so the plants are frugal. They sprout fronds using only about one-third of the nutrients needed by leaves of 56 neighboring species of trees and shrubs. What’s more, coco-de-mer palms can reuse 90 percent of the phosphorus contained in the fronds it’s about to drop.

Seed Size

The coco de mer produces the world’s largest wild fruit and the world’s heaviest seeds. A single seed may be 12 inches long, nearly 3 feet in circumference, and weigh over 40 pounds (20 kg). The seed may take six to seven years to mature and a further two years to germinate. However, germination won’t occur until the palm first reaches plant “puberty.” On the nutrient-poor ground, this reproductive coming-of-age may take 80 to 100 years. Only then can one of these palms yield its first seed. Throughout a female coco de mer palm’s life of several hundred years, it may bear only about 100 seeds.

History and Legends of the Coco de Mer Seed

The coco de mer seed is huge and heavy, and its shape is extraordinarily similar to that of a pair of female buttocks. These two qualities have given the seed a special status around the world.

Because it looks so much like a pair of female buttocks while the male flower is phallic in appearance, the coco de mer seed is the basis of at least two odd legends. According to the first legend, the male and female trees come together for nights of passion when no one is looking. If anyone actually witnesses the love-making, they are struck blind or die. According to the second legend, when Major General Charles George Gordon of the British Army first saw coco de mer seeds, he believed he was looking at the forbidden fruit offered by Eve to Adam in the Garden of Eden.

The coco de mer fruits, which contain the seed and are surrounded by a husk, are very heavy. When they fall into the sea, they sink to the bottom. After a period of time, the husk falls away and the fruit decays; gases form as a result, causing the seed to rise to the surface of the water. Over the centuries, sailors have discovered these huge floating seeds and believed them to the seeds of “sea coconuts.” This led to the name coco de mer, or “coconut of the sea.” The very rare seeds were highly prized; princes and emperors paid dearly to own them.

The world's largest seed comes from the coco de mer palm. Learn about the tree, the seed, and the legends that surround them.

Double coconut: The largest seed in the world

How did the double coconut, one of the natural world’s most celebrated and mysterious phenomena, evolve on a remote island?

On the beautiful islands of the Seychelles in the Indian Ocean grows a legendary palm. Lodoicea maldivica, also known as the double coconut, or coco-de-mer, is renowned for producing the largest and heaviest seeds in the world.

With their rather suggestive shape and weighing up to an impressive 25kg, while measuring up to half a metre long, these spectacular seeds are attractive to scientists, tourists and poachers alike.

Legend has it that the double coconut possesses medicinal properties. Although these “healing powers” remain unproven, the palm remains of high interest as an aesthetic wonder, with single nuts currently sold for £500-£2,000.

Large seeds at a big risk

Due to overharvesting, there are now only around 8,000 wild mature Lodoicea palms on just the two islands of Praslin and Curieuse.

The species is listed as Endangered on the IUCN Red List of Threatened Species.

To protect them from going extinct, seeds in the wild and in botanical gardens worldwide that have manged to grow them, are carefully guarded, sometimes even placed in cages, to prevent poaching.

Palms closely related to the double coconut also produce seeds that are among the largest in the world, and far larger than most other palm seeds – although much smaller than those of the double coconut (up to 10cm long).

Studying Lodoicea could provide the key to understanding the evolutionary forces that lead plants to produce very large seeds.

From the island to the lab

Here at Kew, we’ve been trying to understand what could have triggered the evolution of large seeds in Lodoicea and its relatives, and what could have led to the extreme size of the double coconut.

To do that, we combined and analysed data from DNA, seed sizes, and other information about the shape, structure and ecology of these palms.

Our study reveals that several conditions had to be met, in a specific order, to allow the double coconut to exist.

The first condition to be met was overall structure. Plants had to be large with few-branched inflorescences (the flowering stem) to physically allow for large seeds.

The second condition was the existence of shady habitats and/or large seed-dispersing animals. This means it was advantageous for plants to have large seeds as they contained resources to sustain seedling growth until they reached the light of the canopy and/or there were animals large enough to be able to disperse them.

Thirdly, a subsequent lack of dispersal agent. Without dispersers, it was advantageous to have fewer seeds to minimise plant competition under the ‘mother tree’. And because fewer seeds were produced, they could be even larger.

The relatives of the double coconut stopped at the second condition, which likely favoured the evolution of their large seeds.

Some of their ancestors then dispersed to the Seychelles, islands devoid of large seed-dispersing animals (third condition), allowing the gigantic seeds of Lodoicea to evolve.

What we don’t know is whether Lodoicea will continue to evolve towards even bigger seeds.

What is lost is lost

The unique gigantism of the double coconut reminds us that time and chance – in this case having already large seeds, randomly landing on a small island without big animals and staying there for thousands of generations – can drive the evolution of diverse features.

Lodoicea is protected but many other plants are facing extinction, together with the services that they provide to nature and humanity.

These services too, are the result of a long and contingent evolution. Recreating them once they are extinct will be much more difficult, often impossible, and more costly than saving them from extinction from the start.

How did the double coconut, one of the natural world’s most celebrated and mysterious phenomena, evolve on a remote island?