Give a concise account on steps involved in fertilization of an angiosperm plant.

Explanation

Fertilization is a phenomenon in which the male gametes released from a male gametophyte fused with the egg nucleus to form a zygote. In angiosperms, this phenomenon is called double fertilization because both the male gametes are involved in fertilization. One of the male gametes fuses with the egg nucleus to form a zygote while, the second gamete migrates to the centre of the ovule and fuses with polar nuclei to form the Primary Endosperm Nucleus (PEN). This phenomenon is called triple fusion, because three nuclei are involved in this fusion. This subsequently forms the endosperm which supplies nutrition to the growing embryo.