The Common Coconut

This science article investigates the seed dispersal, germination and growth of the common coconut. (Cocos nucifera)

Sunset with silhouette of coconut palmtree, Fiji

 Fruit of the Common Coconut

In botanical terms, a coconut fruit is best described as a dry drupe.  A dry drupe has an outer fleshy skin surrounding a dry husk; the dry husk encases a hard shell; it is the hardened shell which contains the seed.

dry drupe of coconut showing husk (mesocarp) fleshy skin (exocarp) and hard shell (endocarp)

Contrast the dry drupe of the coconut with the wet drupe of a peach.

peach endcocarp exocarp and mesocarp

The seed (or nut) of an immature fruit contains a lot of water (also called liquid endosperm). The water provides nourishment to help the growth of the ‘meat’, or solid endosperm, inside the hard shell of the fruit.

seed of coconut cocos

So the greatest amount of coconut water is found in the young, immature fruits.

green coconut containing liquid endosperm, sold in pangandaran, indonesia

As the fruits mature as they grow on the palm tree, the amount of water in the seeds decreases at the same time as the amount of meat increases.

coconut ripens on the tree

Natural dispersal across oceans

Growing naturally in the wild, the common coconut has the ability to disperse its seeds very effectively across oceans.

After falling off a palm tree…

coconut palms growing on the coast near Galle Marianne North 1876Royal Botanical Gardens: Marianne  North  1876

the plant’s thick, dry husk prevents damage to the coconut as it falls to the ground from even the tallest of palm trees.

image of coconuts, together with husks, growing high up in a palm tree

The dry husk keeps the coconut buoyant as it drifts thousands of miles through ocean currents.

The husk also prevents sea water seeping into the shell destroying the nut. A coconut can survive in seawater for anything up seven months….

coconut floating in water

until it makes landfall on a beach.

coconut in sea washed up on the beach

If it is washed ashore in high winds above the high tide mark, it stands a good chance of germinating.

coconuts germinating above high tide mark on Mile Atoll , Micronesia

 Germination of the Cocos nucifera

After being swept onshore above the high tide mark it will start germinating once it comes into contact with fresh water. The embryo (labelled A) now starts to grow and develop.

developing coconut embryo© waynes

It pushes upwards into the seed cavity…..

Coconut cotyledon growing into seed cavity© waynes

where it becomes significantly enlarged.

coconut apples or cotyledon growing inside seed cavity

The embryo  is now called a cotyledon; the cotyledon develops into a spongy mass which absorbs the nutrient rich flesh and water of the coconut. It is the cotyledon, seen below the shell removed, which supplies the growing shoots and roots with sugar and minerals.

coconut cotyledon with shoots and roots still attached©

In this image the husk has been removed; in the wild the roots and shoots grow through one of three eyes (or germination pores) in the hard shell…

germinating coconut with husk removed©

and through the husk…

cross section coconut revealing shoots and roots

to produce saplings.

coconut germinating on a beach in Australia

It was the three germination pores that has given the coconut its name; in 1498 by sailors of the Portuguese explorer Vasco da Gama discovered the fruit growing in East Africa. The three germination pores reminded the sailors of a monkey’s face, or macaco, in Portuguese.

coconut endocarp showing germination pores

Drifting across oceans is not the only way in which the coconut disperses its seeds. Like its endangered cousin, the Coco de Mer palm tree, the Common Coconut also disperses its seeds by gravity. In this image you can see how a seed has dropped and taken root very close to the parent tree.

seed dispersal by gravity; young coconut palm growing underneath parent palm© Dr Roland Bourdeix

As with other forms of seed dispersal, it is often a matter of chance whether a seed is able to germinate, put down roots and establish itself.

  • Will the coconut germinating on this beach be able to put down roots?

coconut germinating on beach surrounded by husks of other coconuts

Seed dispersal by humans

Throughout the centuries humans have dispersed coconut palms far from their ancestral homelands in South East Asia

coconut spread        © Natural History Museum, London

Today coconut palms can be found in most coastal tropical countries of the world.

map showing distribution of coconuts around tropical and sub tropical regions of the world

As human have dispersed coconut palms in tropical regions around the globe they have engineered changes to coconuts. Wild varieties have elongated, thick husks and small nuts.

wild coconut niu kafa© waynes

By way of contrast, domesticated varieties have larger, more spherical nuts; the larger nuts contain more meat ( or endosperm)

coconut with husks drying in the sun

There are many different varieties of domesticated coconut; these are but a few of them:

types and variety of Cocos nucifera coconuts showing fruits and cross sections© Dr Roland Bourdeix

There are also many different sizes of palm tree from tall to dwarf.

different sub species of coconut palm tall and short

  • So why has the common coconut been so widely domesticated?

The common coconut, one of 1500 species in the palm (Palmaceae) family, is a plant which humans use in many different ways. To quote a proverb from the Philippines;

“He who plants a coconut tree, plants pots and clothes, food and drink, a house for himself, and an inheritance for his children.”

All parts of the coconut and palm tree can be used in one form or another. These are just a few of the many uses of the Cocos nucifera:

Leaves are woven to make roofs for houses….

weaving coconut leaves to make roofs

and the mid ribs of leaves used to make brooms.

man making coconut brooms from mid ribs top image:

The fibres (coir) from the husks are woven to make coir rope…

Making coir rope from coconut husks in Kerala, india

and coir carpets.

making a rug from coconut fibres in endocarp husk coir in Sri Lanka

The meat is used to make coconut milk…..

making coconut milk from solid endosperm coconut

….and beauty products.

coconut beauty products

The spathe (see below ) is used to make fruit bowls.

spathe containing inflorescence of coconut used to make fruit bowls

Reproduction of Cocos nucifera

Immature flowers are housed in a protective sheathe called a spathe.

inflorescence spathe cuban royal palm Roystonea

As the flowers mature the protective sheathe opens out to reveal the flowers.

cocos nucifera male and female flowers enclosed in a sheath
The male and female flowers are both found on the same inflorescence. The more numerous smaller male flowers are are found at the top of each stem; the larger, round female flowers are located at the bottom.

Cocos nucifera male and female flowers
In this image you can see both male and female flowers emerging on different stems out of their protective sheathes.

coconut inflorescence showing male and female flowers emerging from their sheath

Pollen is dispersed from male to female flower by the wind or by insects. It is the female flowers which grow into coconuts. With natural pollination, 50 to 70% of the fruits either fall off or never mature into adult fruits. Once pollinated it takes 12 months for the female flowers to develop into fully mature fruits.

coconut flowers blooming on palm tree

Some varieties of coconut palm, such as this Malayan Red Dwarf variety below, self pollinate. Pollen grains from the stamens of male flowers are transferred to the ovules of female flowers on the same  tree. This method of pollination provides an evolutionary advantage to coconut palms which grow in areas with few insects.

red dwarf palm trainee

Other varieties of coconut palm cross pollinate; the pollen from the male flowers of one tree is transferred to the female flowers of a different tree.

Cocos nucifera, Manzanilla Bay, Trinidad

Yet other types of coconut pollinate using insects to transfer the pollen from the male flower of one tree to the female flower of a different tree.

 pollination of coconut palm by a wasp © trainee agriculturist.blogspot

Coconut fun stuff

  • Look at these coconut freaks
  • Listen to this song about the amazing variety of uses for the coconut.

Post a Comment

One Response to “The Common Coconut”

  1. Sreedhar says:

    Nicely presented. Very informative and systematic.

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