When I picture tropical islands, I see long rows of coconut palms. They thrive on shorelines all around the equator, thanks to their amazing ability to disperse. The husk that surrounds their internal seed can float for many months across the ocean. And the seeds can germinate as soon as they reach shore.
But their cousin, the double coconut, is just the opposite — it’s a complete homebody. It grows naturally on only two tiny isolated islands in the Indian Ocean.
Why don’t double coconuts disperse to other places? Because their seeds are enormous, the biggest in the world! Each seed can be two feet long and weigh over 50 pounds! And the massive fruit that surrounds the seed can top 90 pounds. Too heavy to float, they sink into the ocean, instead of drifting away.
Each seed takes nearly a decade to mature. It sends out a single long root, or “sinker,” which can stretch 30 feet, to place the sapling beyond the shade of its parent.
Centuries ago, people who found these huge nuts washed ashore believed they came from palms that grew underwater, and named them coco de mer, meaning “sea coconut.” Their true home wasn’t discovered until 1768, when a French explorer traced them to the Seychelles.
Today, fewer than 8,000 wild trees remain. Once prized as magical charms and fertility symbols, their nuts are still collected, despite international laws.
Happily, botanic gardens worldwide are cultivating them — sometimes under tight security — to ensure that this amazing tree survives.
