Double coconut: The largest seed in the world

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.