Sexual Reproduction in Flowering Plants

About this unit

This unit explains how flowering plants (angiosperms) reproduce sexually. It follows the story from the flower, the site of reproduction, through the formation of male and female gametophytes, pollination, double fertilisation and the development of seeds and fruits. It also covers unusual routes such as apomixis and parthenocarpy. The topic links directly to agriculture, plant breeding and food production, which is why it is a favourite area for conceptual questions.

Key ideas

• The stamen (anther + filament) is the male organ; the pistil (stigma, style, ovary) is the female organ.
• Microsporogenesis forms pollen grains; megasporogenesis forms the embryo sac.
• The typical embryo sac is 7-celled and 8-nucleate.
• Pollination may be self (autogamy, geitonogamy) or cross (xenogamy), aided by wind, water or animals.
• Double fertilisation produces a diploid zygote and a triploid primary endosperm nucleus.
• Seeds and fruits develop after fertilisation; apomixis and parthenocarpy are special cases.

How to prepare

Practise drawing and labelling the anther cross-section, a pollen grain, an anatropous ovule and the embryo sac. Memorise the ploidy of each structure (nucellus, endosperm, zygote, synergids). Expect matching questions on pollinating agents and assertion–reason questions on outbreeding devices.