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grains from the anther to the stigma is necessary for fruit formation. The transfer of pollen grains from the anther to the stigma of a flower is called pollination. Self-pollination Stigma Anther 11.2.3 How does the process of pollination occur in flowers? In the Activity 11.6, we stated that the process of pollination is the transfer of pollen to the stigma of a flower. The transfer of pollen occurs to the stigma of the same flower or another flower of the same plant, is called self-pollination (Fig. 11.13). Cross-pollination If the pollen is transferred from the anther of a flower of one plant to the stigma of a flower of another plant of the same type, the pollination is called cross-pollination (Fig. 11.13). The transfer of the pollen grains to the stigma is important for the formation of fruits and seeds. Nature has provided plants with various strategies for pollination to occur. What do you think will Fig. 11.13: Self and happen if pollination does not occur? Cross-pollination 11.2.4 Pollination strategies and reproductive success Pollination depends on external agents called pollinators, such as wind, water, insects (bees, butterflies), or birds. Pollination by wind is seen in plants like wheat, maize and rice, where pollen grains are light and small, produced in large numbers, and the stigma is long and feathery to trap them. In aquatic plants, such as Vallisneria and Hydrilla, pollination occurs through water, with currents carrying the pollen from one flower to another. Many plants, including sunflower, Pollen grain hibiscus and marigold are pollinated by insects, such as bees and Stigma butterflies. Their flowers are often brightly coloured, produce nectar, Male and give off fragrance to attract pollinators. The pollen grains are germ cell large, sticky or spiny, so they can attach to the insect’s body and the Pollen tube stigma is also sticky to receive them. Some flowers like those of the coral tree and hibiscus plant, are pollinated by birds, such as Indian Ovary white-eye and sunbirds. Let us see how fruits and seeds are formed. Ovule 11.2.5 Fertilisation and seed formation Egg cell Fig. 11.14: Germination ofOnce the pollen reaches a compatible stigma, a remarkable process pollen on stigma begins. Pollen grains produce pollen tubes that grow down through the style into the ovary. The male gamete moves through this tube and arrives at the ovule, where it fuses with the egg cell (Fig. 11.14). This fusion of gametes is referred to as fertilisation and it marks the beginning of a new life. The fertilised egg is called a zygote, which later develops into an embryo. In the meantime, the ovary surrounding the ovules enlarges and develops into a fruit, while the ovules develop into seeds inside it (Fig. 11.15). Seed dispersal takes place by wind or water and animals. When conditions like water, air and temperature are favourable, the seed germinates and grows into a new plant. Fig. 11.15: Transformation of Thus, sexual reproduction not only produces new plants but ovary to a fruit also creates variation, helping plant species survive and adapt to their environment. 216 Exploration|Grade 9