Post Fertilisation Structures And Events

The cells of lower tier divide twice to form three tier of four cells each. At this stage the proembryo consists of cells arranged in four tiers. Each tier has a specific function.
(i) The lowermost tier is known as the embryonal tier, its cells divide to form embryo
(ii)The cells of the next tier called suspensor tier elongate to form suspensor.
(iii) The cells of tier, known as the rosette tier conduct nourishment to the embryo.
(iv) The uppermost tier consisting of incomplete cells is known as nutritive tier and it provides nutrition.

In Cocos nucifera (coconut), the epicarp is membranous, mesocarp is fibrous (hence, called fibrous drupe and yields coir) and the endocarp is stony.