Plants often give off a mundane vibe, but some species boast remarkably unique adaptive features.
Take the Coco de Mer palm tree, for instance. This tree is touted as the only plant that can rival the giant panda in terms of distinctiveness, breaking a whopping 11 botanical records.
What's even more intriguing is that legends of this plant circulated across three continents—Asia, Europe, and Africa—long before its discovery. This was due to its peculiar seeds, which occasionally washed up on the shores of the Indian Ocean and were picked up by curious individuals.
The image above shows the seed of the coco de mer palm, which is remarkably large, with a diameter of up to 50 centimeters and weighing up to 17.6 kilograms, making it the largest seed in the world.
When you see such a seed, you might wonder what it reminds you of. Interestingly, in the coastal regions of the Indian Ocean, people have traditionally associated it with the human buttocks and believed it possesses magical powers for men. This belief persists to this day, contributing to the seed's enduring value and rarity.
Now, what exactly is the coco de mer palm, and why do its seeds grow to be so enormous and peculiar? And how do these plants manage to spread their seeds?
Coconut Palms on Deserted Islands
Coconut palms thrive on deserted islands, and when their seeds fall into the ocean, ocean currents carry them to the shores of the Indian Ocean. This was initially the only way people came into contact with these seeds (although it's not how they spread their seeds, as I'll explain later), making them highly sought after due to their uniqueness, rarity, and mystique.
Among these places, the Maldives is where coconut palm seeds often land—it was previously one of the most prolific producers of these seeds.
Residents of the islands were required to surrender any found seeds to the king, under penalty of death. The king would typically gift these seeds to the most esteemed international friends, highlighting their value in ancient times.
Until 1768, people didn't know what kind of plant these seeds came from, but they believed them to be seeds of some sort of tree.
Legend has it that this tree grows at the bottom of the sea, colossal in size, with fruits meant for a gigantic bird to consume. Similar tales are widespread along the coasts of the Indian Ocean, with some Africans even believing that these enormous birds prey on elephants.
Image: Artwork made from coco de mer seeds
With the arrival of great voyages, French explorer Marc-Joseph Marion du Fresne visited the uninhabited Seychelles Islands and finally discovered the trees producing these giant seeds on Praslin and Curieuse Islands — the only known places where coco de mer palms grow.
Once this became known, in 1769, a man named Jean Duchemin saw an opportunity. He sailed to the Seychelles Islands to harvest these seeds, filling an entire ship on his first visit to sell them in the markets of India.
Since then, the mystique and extraordinary value of coco de mer seeds have diminished, but they remain highly prized and expensive.
That's the basic story of coco de mer seeds, but as exploration of them continues, people are discovering just how unique these trees truly are.
The coconut palm is quite remarkable. From its appearance, it may seem like just another palm tree, but there are some peculiarities that set it apart. Everything about it is large, yet everything happens slowly.
It boasts the largest seed in the plant kingdom, and consequently, it produces the largest wild fruit in the world, weighing between 36 to 47 kilograms. It's worth noting that these are wild fruits; cultivated ones can be even larger.
Coconut palms are dioecious, meaning they have separate male and female plants. To produce such enormous fruits, they have the largest female flowers in the plant kingdom, along with the largest ovaries and sepals. Interestingly, their male flowers also have the longest inflorescence in the plant kingdom, reaching up to 2 meters long, although the significance of such length remains a mystery.
To grow these organs to such massive proportions, coconut palms employ a strategy of extending their growth cycles, which explains why everything about them happens slowly.
Firstly, the growth rate of these plants is exceptionally slow. For instance, a coconut palm planted in the Peradeniya Royal Botanical Gardens has been recorded to grow only 33 millimeters per year on average over a span of 140 years, making it the slowest-growing among all known large trees.
A characteristic feature of palms is the elongated trunk topped with a crownshaft. The crownshaft of a coconut palm typically consists of around 20 fan-shaped fronds, each with a diameter of about 10 meters.
However, it takes 9 years just for the crownshaft to develop, followed by another 9 years for the fronds to fully function. Many other palm species don't even live up to 18 years (although coconut palms are believed to live up to 200 years).
Once fully developed, each frond can last up to 24 years, making them the longest-lived among all monocots.
Their fruit takes a whopping 8 to 10 years to mature, the longest period among all plants. If conditions permit, it takes two years for the fallen fruit to germinate. However, palm seeds can remain viable for a long time, which seems to make up for the lengthy process.
However, when their seeds sprout, they grow the longest cotyledons in the plant kingdom, reaching up to 10 meters, unmatched by any other plant's cotyledons.
What makes the coconut palm tree as unique as the giant panda is the plethora of highly specialized features they share.
But regardless of how organisms specialize, it's all about enhancing survival and reproductive capabilities in specific environments.
Speaking of reproduction, let's circle back to their unique seeds, which harbor many scientifically puzzling aspects.
Unspreadable seeds?
It's common for organisms on islands to evolve into larger forms than their mainland relatives, a phenomenon known as island gigantism.
However, some organisms on islands tend to become smaller over time, a condition termed island dwarfism, like the dwarf elephants of Mediterranean Crete. They were the last surviving group of mammoths, with adult individuals standing only 1 meter tall and weighing just 150 kilograms, resembling larger wild boars.
Image: Dwarf mammoths of Crete, shorter than humans
The sea coconut's large seed is just a manifestation of island gigantism, but what makes it unique is that it's the only plant in the entire Seychelles archipelago to exhibit gigantism.
Plants, being immobile, need to spread their seeds farther to avoid competition with their offspring. Depending on the environment, they typically have several methods: wind, water, and animal digestive tracts.
Most seeds we're familiar with are dispersed by animals. These plants grow enticing fruits to attract animals for consumption. The indigestible seeds are then carried away to distant places within the animal's digestive tract.
Many island plants tend to rely on sea water for dispersal. The familiar coconut palm, for instance, employs this method, which is why its fruits have tough shells to resist sea erosion.
The sea coconut, also a typical island palm, has fruits that sink directly to the seabed instead of drifting with the currents.
Those seeds that wash up on the shores of the Indian Ocean actually float after rotting internally, causing them to become buoyant and drift with the currents until picked up by coastal residents.
Of course, relying on animals or nature for such large seeds is impractical, which is why they are confined to just two isolated islands in the Seychelles archipelago, unable to spread beyond.
So, what's the point of such large seeds?
Many might see this seemingly illogical feature and wonder if organisms have stumbled into an evolutionary dead-end, turning what should be advantageous traits into burdens.
But that's not the case. The coco de mer palm hasn't hit an evolutionary dead-end; on the contrary, it thrives in its habitat with an overwhelming dominance — about 80% of the trees in the forests of its two islands are this species.
The reason its seeds currently lack dispersers isn't because they've grown larger, but rather because they lost their dispersal mechanism before reaching their current size.
Researchers in this field suggest that around 66 million years ago, the ancestors of the coco de mer relied on animals to disperse their seeds. However, as the Seychelles Islands began to drift away from the Indian subcontinent, the coco de mer became isolated on these islands, losing its animal dispersal mechanism.
But why did the seeds become so large afterwards?
This is actually caused by island syndrome.
Larger seeds have an advantage because seedlings can grow faster and better, which is crucial on islands. Therefore, island plants tend to have larger seeds.
Before being isolated on islands, coconut palms may have had relatively large seeds themselves. So, as isolation occurred, they quickly outcompeted rivals, becoming the dominant population in their habitat.
Since their seeds couldn't be dispersed away, they turned to competition within the population, leading to intense internal competition, or what we call crazy "seed binging."
Without the need to consider seed dispersal, larger seeds became possible. Meanwhile, living space was extremely limited. To grow faster than their siblings, they began to crazily enlarge their seeds.
This eventually led to the development of these disproportionately large seeds.
You may have one last question: If they can't spread their seeds, does their reproduction mean they're competing with themselves in their surroundings?
Indeed, that's the case. Some even believe their seeds only sprout when the parent plant dies.
Though not quite as dramatic as one life for another, that's essentially how it happens. By the time the seeds sprout and flower, the parent plant is nearing the end of its days.
These plants have two other intriguing features that set them apart from others. Their leaves contain only about one-third of the nitrogen and phosphorus concentration compared to other trees in the Seychelles Islands. They allocate most of these nutrients to the seeds, leaving themselves somewhat malnourished.
Moreover, their leaves excel at channeling dead flowers, leaves, bird droppings, and other matter into the soil around their roots. This results in soil within 20 centimeters of the trunk containing at least 50% more nitrogen and phosphorus compared to soil 2 meters away—a phenomenon observed only with them.
Of course, this feature is mainly due to their seeds, which typically only fall within this area.
Nevertheless, the coco de mer palm is indeed comparable to the giant panda. Sadly, like the panda, they're now endangered, with fewer than 8,000 mature individuals left in the wild.
Their peculiar endangerment is solely due to their seeds resembling human buttocks, leading to excessive harvesting.
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