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not possible. Plants may be monocios, e Maize or diecious, eg Mulberry, Papaya it different times in a bisexual flower so as to prevent self pollination It can be further divided into two types 1. Protandry: In this type, androecium matures earlier than the gynoecium, e.g. in the disc florets of sunflower. 2. Protogyny: In this type, gynoecium matures earlier than the androecium, e.g. Gloriosa. Prepotency: Pallen grains of other flowers germinate rapidly over the stigma than the pollen grains from the same flower, e.g. Apple. Heterostyly (heteromorphy): In some plants like Primula (Primrose, there are two or three forms/ types of flowers in which stigmas and anthers are placed at different levels (heterostyly and heteroanthy). This prevents the pollens from reaching the stigma and pollinating it. In heteromorphic flowers, pollen grains produced from anther pollinate stigmas produced at the same level. Herkogamy: It is a mechanical device to prevent self pollination in a bisexual flower. In plants, natural physical barrier is present between two sex organs and avoid contact of pollen with stigma of same flower, e.g. Calotropis- pentangular stigma is positioned above the level of anthers (pollinia). Seif incompatibility (self sterility): This is a genetic mechanism due to which the germination of pollen on stigma of the same flower is inhibited, c.g. Tobacco, Thea. Do you know? in all breeding programmes, the plants

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Updated on: Nov 9, 2022