Coconut: From Fruit to Tree
The seed germinates slowly, taking up to 4 months before the shoot appears. During germination, the single cotyledon (seed leaf) grows inside the seed cavity. After two weeks, it hardens a little and then begins to form the first root on the underside, followed by the shoot on the upper side. It also grows a sheath to protect the seedling root and shoot from insects and mammals. This grows with them through the softest of the three eyes at the base of the shell.
At the same time, the embryo develops an organ of spongy tissue (technically, the haustorium, but often called the ‘apple’) that expands rapidly into the cavity of the nut, usually filling it completely within four months, although in a large nut this would take a little longer. It rapidly absorbs the coconut water, and from the kernel it takes nutrients at an increasing rate to provide substance and energy for the growth of the seedling. Because the seedling has this natural reservoir, it can grow for some time before making contact with the soil.
When the first green leaf appears, the seedling can begin to generate its own food by photosynthesis and there is a period of gradual ‘weaning’ as the young seedling expands a series of leaves, each larger than the one before. Each new leaf supplies a greater share of the energy needs of the seedling, which thereby becomes less and less reliant on the diminishing kernel to sustain its accelerating growth.