Assertion : Nuclear endosperm is formed by subsequent nuclear division without wall formation. Reason : Coconut is an example of such endosperm, where the endosperm remains nuclear throughout the development of the fruit.

Step-by-step solution

In nuclear endosperm, first and further divisions of primary endosperm nucleus are not followed by cytokinesis or wall formation and thus these free nuclear divisions lead to formation of a large number of free nuclei in embryo sac. At maturity, centripetal wall formation may occur to make the tissue partly cellular. Endosperm of coconut is unique in sense that it is both nuclear and cellular. Here the primary endosperm nucleus undergoes a number of free nuclear divisions. When the fruit is about 50 ~mm long the em