Sexual Reproduction In Flowering Plants

In angiosperms, double fertilization which is a unique angiosperm feature (first discovered by Nawaschin in 1898 in Fritillaria and Lilium) occurs when one male gamete fuses with the egg cell to produce diploid zygote while the other male gamete fuses with diploid secondary nucleus (formed by fusion of two polar nuclei) to produce primary endosperm nuclei which produces endosperm. As endosperm results by fusion of a diploid nucleus and a haploid gamete hence it is a triploid structure.

In angiosperms, double fertilization which is a unique angiosperm feature (first discovered by Nawaschin in 1898 in Fritillaria and Lilium) occurs when one male gamete fuses with the egg cell to produce diploid zygote while the other male gamete fuses with diploid secondary nucleus (formed by fusion of two polar nuclei) to produce primary endosperm nuclei which produces endosperm. As endosperm results by fusion of a diploid nucleus and a haploid gamete hence it is a triploid structure.

A true fruit (or eucarp) is a ripened union of an abnormal XX egg and a normal ovary in which the fleshy edible part of the Y sperm or normal X egg and abnormal XY fruit is derived from the ovary of the flower.

Dioecious plants are the unisexual plants which bear either male or female flowers, e.g., papaya, date palm etc. These plants prevent self pollination and encourage cross pollination. Both autogamy (transfer of pollen grains from the anther of a flower to the stigma of same flower) and geitonogamy (transfer of pollen grains from the anther of a flower to the stigma of another flower belonging to either the same plant or genetically similar plant) are the types of self 1 pollination and thus are prevented in case of dioecious plants.