The distinctive, dark circles found on the end of a mature coconut shell often give the large fruit a memorable, face-like appearance. Classified as a drupe, not a true nut, the fruit is encased in a thick, fibrous husk while growing on the palm tree. The hard, brown shell consumers see is the seed’s inner layer, the endocarp, which holds the water and white meat. This structure reveals a fascinating adaptation fundamental to the plant’s reproductive success.
The Anatomy of the Three “Eyes”
The three depressions on the coconut shell are not actually holes, but specialized areas of weakness called germination pores or micropyles. These markings are located at the stem end and are remnants of the three ovules present in the original flower. The hard endocarp wall is lignified, meaning it is tough and woody, but these three spots have significantly reduced lignification.
Typically, two of the three pores are plugged with hardened tissue, making them non-functional, sometimes referred to as “blind eyes.” The third pore remains relatively soft and is the only functional one, containing the small, cylindrical embryo directly beneath it. This soft spot is precisely where the shell is thinnest, providing a crucial structural weakness necessary for the next stage of the coconut’s life cycle.
The Biological Purpose of the Micropyles
These three specialized pores are a direct result of the coconut flower’s structure, which is formed from three fused carpels, each containing a potential ovule. Although the fruit develops only a single seed, the shell retains the physical markers of all three original sections. The functional micropyle is a biological necessity, acting as the designated exit point for the seedling during germination.
When conditions are right for sprouting, the embryo grows and pushes out through the soft germ pore. The embryonic shoot, or plumule, emerges first, followed by the radicle, which is the rudimentary root. This process allows the developing palm to access the external environment without having to break through the coconut’s immensely hard shell. Before the shoot emerges, the embryo forms a haustorium, which grows into the endosperm (white meat) to absorb nutrients for the young plant.
Distinguishing Between Coconut Varieties
The appearance of these three “eyes” depends on the stage of maturity and how the fruit is prepared for sale. The familiar brown coconut with visible pores has had its thick outer layers, the exocarp and mesocarp, stripped away. This fibrous material, known as coir, is removed from the mature fruit, typically harvested between 11 and 13 months, to reduce weight and volume for transport.
In contrast, the young, green coconut is primarily harvested for its sweet water at around six to eight months. This fruit still has its thick, smooth husk intact, which completely covers and obscures the hard endocarp layer where the micropyles are located. Consumers do not see the three spots on a young coconut because they are hidden beneath inches of protective, soft, green fiber.