Sexual Reproduction in Flowering Plants

 Sexual Reproduction in Flowering Plants

 

What we will Learn? Sexual Reproduction in Flowering Plants Sexual reproduction in plant is the fusion of male cell and female cell (egg cell or ovum) to form third cell known as zygote. Zygote develops into a new plant over period of time. Flowers are the reproductive organ in plants. So, before we study the concept of sexual reproduction in plant, let us learn about various parts of flower. The flowers are of two types. Some flowers have both male and female reproductive organs. (Bisexual) Example: Rose, sunflower, hibiscus, mustard, rose etc Some flowers contain only male or female reproductive organ.(Unisexual) Example: Watermelon, cucumber , papaya etc. The female part of flower The female part of the flower is the pistil. The pistil usually is located in the center of the flower and is made up of three parts: the stigma, style, and ovary. The stigma is the sticky knob at the top of the pistil. It is attached to the long, tube like structure called the style. The style leads to the ovary that contains the female egg cells called ovules. The male part of flower The male parts are called stamens and usually surround the pistil. The stamen is made up of two parts: the anther and filament. The anther produces pollen grains which contains male reproductive cells. The filament holds the anther up. Sepal: The outer parts of the flower (often green and leaf-like) that enclose a developing bud. Ovary: The enlarged basal portion of the pistil where ovules are produced. Petals are the colorful part of the flower that attracts insects and even other small animals, such as mice, birds, and bats. How pollination takes place? Sexual reproduction in plants occurs when the pollen from an anther is transferred to the stigma. Plants can fertilize themselves: called self-fertilization. Self-fertilization occurs when the pollen from an anther fertilizes the eggs on the same flower. Cross-fertilization occurs when the pollen is transferred to the stigma of a different flower of same kind. The process of transference of pollen grains from the anthers to the stigma is called pollination. Pollination occurs in several ways. Animals, Insects and winds usually help in transfer of pollen from one flower to another. Bees, butterflies, moths, flies, and hummingbirds pollinate plants. When animals, birds or insects are attracted towards plant to get food, the sticky pollen or a sweet nectar made at the base of the petals rub against the stamens and get pollen stuck all over themselves. When they move to another flower to feed, some of the pollen can rub off onto this new plant's stigma. Another way plants are pollinated is by the wind. The wind picks up pollen from one plant and blows it onto another. Process of fertilization During the process of fertilization, pollen lands on the stigma, a tube known as pollen tube grows down through the style and enters the ovary. Male reproductive cells in pollen tube travel down the tube and join with the ovule, fertilizing it to form the zygote. The fertilized ovule becomes the seed, and the ovary becomes the fruit. The fruit is the ripened ovary of a plant containing the seeds. After fertilization, the ovary swells and becomes either fleshy or hard and dry to protect the developing seeds.