Why do coco-de-mer seeds grow so large?

BBC Wildlife section editor Sarah McPherson answers your wild question.

A
a
-
Coco-de-mer seed

Coco-de-mer seed © Buena Vista Images / Getty

 

Trees that colonise isolated islands often develop bigger seeds. No species demonstrates this evolutionary pattern more than the coco-de-mer, a native of the Seychelles, whose record-breaking seeds can reach a whopping 40-50cm in diameter.

When the Seychelles split from the mainland, these trees became cut off from the animals they relied upon for seed dispersal. Seeds that fell thus stayed put, growing close to – and competing with – their parents, siblings and cousins.

“This exerted pressure on seed size: the larger the seed, the higher the chance of establishment and survival,” says Christopher Kaiser-Bunbury, a scientist at the Technical University of Darmstadt in Germany. Christopher and colleagues have discovered how the coco-de-mer, which grows in very poor soil, is able to sustain such colossal seeds: it uses its leaves as a funnel-and-gutter system that harvests rainwater and diverts it to the base of the trunk.

As the liquid descends, it collects a host of phosphorus-rich material, creating a nutritious soup that feeds the soil immediately around the tree. 

 

Click here to read more of our Wildlife Q&As.

Do you have a wildlife question you’d like answered? Email your question to wildquestions@immediate.co.uk or post it to Q&A, BBC Wildlife Magazine, Immediate Media Company, 2nd Floor, Tower House, Fairfax Street, Bristol BS1 3BN

We use cookies to improve your experience of our website. Cookies perform functions like recognising you each time you visit and delivering advertising messages that are relevant to you. Read more here