Sexual Reproduction in Flower
CHAPTER 2
SEXUAL REPRODUCTION IN FLOWERING PLANTS
2.1 2.2 2.3 2.4 2.5 Flower – A Fascinating Organ of Angiosperms Pre-fertilisation : Structures and Events Double Fertilisation Post-fertilisation: Structures and Events Apomixis and Polyembryony
Are we not lucky that plants reproduce sexually? The myriads of flowers that we enjoy gazing at, the scents and the perfumes that we swoon over, the rich colours that attract us, are all there as an aid to sexual reproduction. Flowers do not exist only for us to be used for our own selfishness. All flowering plants show sexual reproduction. A look at the diversity of structures of the inflorescences, flowers and floral parts, shows an amazing range of adaptations to ensure formation of the end products of sexual reproduction, the fruits and seeds. In this chapter, let us understand the morphology, structure and the processes of sexual reproduction in flowering plants (angiosperms).
2.1 FLOWER – A FASCINATING ORGAN OF ANGIOSPERMS
Human beings have had an intimate relationship with flowers since time immemorial. Flowers are objects of aesthetic, ornamental, social, religious and cultural value – they have always been used as symbols for conveying important human feelings such as love, affection, happiness, grief, mourning, etc. List at least five flowers of ornamental value that are commonly cultivated at
BIOLOGY
Figure 2.1 A diagrammatic representation of L.S. of a flower
homes and in gardens. Find out the names of five more flowers that are used in social and cultural celebrations in your family. Have you heard of floriculture – what does it refer to? To a biologist, flowers are morphological and embryological marvels and the sites of sexual reproduction. In class XI, you have read the various parts of a flower. Figure 2.1 will help you recall the parts of a typical flower. Can you name the two parts in a flower in which the two most important units of sexual reproduction develop?
2.2
SEXUAL REPRODUCTION IN FLOWERING PLANTS
2.1 2.2 2.3 2.4 2.5 Flower – A Fascinating Organ of Angiosperms Pre-fertilisation : Structures and Events Double Fertilisation Post-fertilisation: Structures and Events Apomixis and Polyembryony
Are we not lucky that plants reproduce sexually? The myriads of flowers that we enjoy gazing at, the scents and the perfumes that we swoon over, the rich colours that attract us, are all there as an aid to sexual reproduction. Flowers do not exist only for us to be used for our own selfishness. All flowering plants show sexual reproduction. A look at the diversity of structures of the inflorescences, flowers and floral parts, shows an amazing range of adaptations to ensure formation of the end products of sexual reproduction, the fruits and seeds. In this chapter, let us understand the morphology, structure and the processes of sexual reproduction in flowering plants (angiosperms).
2.1 FLOWER – A FASCINATING ORGAN OF ANGIOSPERMS
Human beings have had an intimate relationship with flowers since time immemorial. Flowers are objects of aesthetic, ornamental, social, religious and cultural value – they have always been used as symbols for conveying important human feelings such as love, affection, happiness, grief, mourning, etc. List at least five flowers of ornamental value that are commonly cultivated at
BIOLOGY
Figure 2.1 A diagrammatic representation of L.S. of a flower
homes and in gardens. Find out the names of five more flowers that are used in social and cultural celebrations in your family. Have you heard of floriculture – what does it refer to? To a biologist, flowers are morphological and embryological marvels and the sites of sexual reproduction. In class XI, you have read the various parts of a flower. Figure 2.1 will help you recall the parts of a typical flower. Can you name the two parts in a flower in which the two most important units of sexual reproduction develop?
2.2