Chapter 16 Reproduction in Plants Summary of pollination in plants 1. The male parts of the flower are the anther and filament 2. The female parts of the flower are the stigma, style and ovary 3. Male gametes are found in Pollen Produced in the Anther 4. Pollen needs to be moved to the female part called the Stigma of the species of plant to reproduce same 5. This process is called Pollination 6. Pollination can be helped by Wind Or Animal 7. An example of wind pollination is grass plants 8. A wind pollinated flower is most likely to look like - small, green, unscented 9. An example of animal pollination is a rose plant pollinated by insects 10.An animal pollinated flower is most likely to look like – colourful, with large petals, perhaps with a scent The Structure and Pollination of an InsectPollinated Flower Structure of Clitoria flower • Belongs to the legume (pea) family External features of Clitoria The Clitoria flower is pollinated by insects. The flower is complete, bisexual and bilaterally symmetrical. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 4 External features of Clitoria pedicel calyx 1 • The calyx consists of five green sepals. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 5 External features of Clitoria pedicel epicalyx calyx 2 • The base of the calyx is enclosed by the epicalyx. The epicalyx consists of two green leaves. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 6 External features of Clitoria pedicel epicalyx calyx corolla • The corolla consists of five brightly-coloured petals 3 of different shapes and sizes. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 7 External features of Clitoria pedicel epicalyx calyx corolla standard petal 4 standard petal • The large, deep blue standard petal has lines on it that guide insects to where the nectar is located. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 8 External features of Clitoria pedicel epicalyx calyx corolla standard petal nectar guide standard petal 4 • The large, deep blue standard petal has lines on it that guide insects to where the nectar is located. • Thus, these lines are called nectar guides. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 9 External features of Clitoria pedicel epicalyx calyx wing petal wing petals corolla nectar guide standard petal standard petal 5 • Two deep blue wing petals are enclosed by the standard petal. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 10 External features of Clitoria pedicel keel petals epicalyx wing petal calyx wing petals corolla nectar guide standard petal standard petal 6 • Two small, yellowish-green keel petals are enclosed by the wing petals. The keel petals enclose the reproductive organs. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 11 Stamens and Pistil of Clitoria Androecium • The androecium consists of ten stamens with long filaments. • The filaments of nine of the stamens are fused along most of their length to form a hollow tube or ‘trough’. This trough encloses the pistil. • Nectar, secreted by the flower, collects at the bottom of the stamen trough. Thus, the nectar can be reached only by an insect with a long tubular mouth or proboscis, for example, a bee or a butterfly. stamen trough stigma Stigma and stamens of Clitoria Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 12 Stamens and Pistil of Clitoria Androecium • The androecium consists of ten stamens with long filaments. • The filaments of nine of the stamens are fused along most of their length to form a hollow tube or ‘trough’. This trough encloses the pistil. • Nectar, secreted by the flower, collects at the bottom of the stamen trough. Thus, the nectar can be reached only by an insect with a long tubular mouth or proboscis, for example, a bee or a butterfly. stamen trough Stigma and stamens of Clitoria stigma The tenth stamen is free. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 13 Stamens and Pistil of Clitoria Pistil The pistil consists of a single carpel. Section of the carpel of Clitoria Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 14 Stamens and Pistil of Clitoria Pistil The pistil consists of a single carpel. Section of the carpel of Clitoria Stigma The stigma is small and compact. It is located at the end of the style. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 15 Stamens and Pistil of Clitoria Pistil The pistil consists of a single carpel. Section of the carpel of Clitoria Stigma Style The stigma is small and compact. It is located at the end of the style. The style is a long, curved, hairy structure. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 16 Stamens and Pistil of Clitoria Pistil The pistil consists of a single carpel. Section of the carpel of Clitoria ovule Stigma Style Ovary The stigma is small and compact. It is located at the end of the style. The style is a long, curved, hairy structure. The ovary is long and narrow with a single row of ovules. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 17 Pollination in an Insect-pollinated Flower (Clitoria) wing petal standard petal keel petal nectar guide stigma stamen trough 1 stamen • In its natural state, the flower is inverted with the standard petal at the bottom. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 19 Pollination in an Insect-pollinated Flower (Clitoria) wing petal standard petal keel petal insect nectar guide stigma stamen trough 1 stamen • In its natural state, the flower is inverted with the standard petal at the bottom. • When a heavy insect such as a bee visits the flower, it lands on the standard petal. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 20 Pollination in an Insect-pollinated Flower (Clitoria) wing petal standard petal keel petal insect nectar guide stigma stamen trough 2 stamen • The insect follows the nectar guide into the flower. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 21 Pollination in an Insect-pollinated Flower (Clitoria) wing petal standard petal keel petal insect entering flower to collect nectar nectar guide stigma stamen trough 3 stamen • The insect forces its way in between the two wing petals and moves in to collect the nectar. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 22 Pollination in an Insect-pollinated Flower (Clitoria) stamen wing petal insect keel petal stamen trough 4 stigma • The insect’s back forces the keel petal upwards to expose the stigma and the anthers. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 23 Pollination in an Insect-pollinated Flower (Clitoria) stamen wing petal insect keel petal stamen trough 4 stigma • The insect’s back forces the keel petal upwards to expose the stigma and the anthers. • The stigma and anthers brush against the hairy back of the insect. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 24 Pollination in an Insect-pollinated Flower (Clitoria) pollen stamen hair grain wing petal insect keel petal stamen trough 4 stigma • The insect’s back forces the keel petal upwards to expose the stigma and the anthers. • The stigma and anthers brush against the hairy back of the insect. • When this happens, some pollen grains from the anther stick to the hairy back of the insect. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 25 Pollination in an Insect-pollinated Flower (Clitoria) pollen stamen hair grain wing petal insect keel petal stamen trough 4 stigma • The insect’s back forces the keel petal upwards to expose the stigma and the anthers. • The stigma and anthers brush against the hairy back of the insect. • When this happens, some pollen grains from the anther stick to the hairy back of the insect. • At the same time, pollen grains on the insect’s back (from another flower which the insect had visited earlier) are Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 26 Pollination in an Insect-pollinated Flower (Clitoria) wing petal standard petal keel petal insect nectar guide stigma stamen trough 5 stamen • When the insect leaves the flower, the keel springs back to its original position to enclose the stamens and the stigma again. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 27 The Structure and Pollination of a Wind-Pollinated Flower Structure of grass flowers (Ischaemum muticum) Structure of Ischaemum muticum pair of flowers • The flowers occur in pairs. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 29 Structure of Ischaemum muticum pair of flowers flowering bract (scale) • The flowers occur in pairs. • Each Ischaemum flower is enclosed by two transparent flowering bracts. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 30 Structure of Ischaemum muticum pair of flowers upper bisexual flower anther feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) • The upper flower is bisexual. It consists of an ovary with two long feathery stigmas, three stamens and two tiny structures called lodicules at the base of the ovary. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 31 Structure of Ischaemum muticum pair of flowers upper bisexual flower anther feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) • The upper flower is bisexual. It consists of an ovary with two long feathery stigmas, three stamens and two tiny structures called lodicules at the base of the ovary. • When Ischaemum is ready to reproduce, the lodicules swell and force the two flowering bracts slightly apart so that the stigmas and anthers Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 32 Structure of Ischaemum muticum pair of flowers upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) • The lower flower is unisexual. It consists of only three stamens with long filaments and two lodicules. Therefore, it is a male flower. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 33 Structure of Ischaemum muticum pair of flowers upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts spikelet filament lodicule flowering bract (scale) • Each pair of flowers, together with a short stalk, forms a spikelet. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 34 Structure of Ischaemum muticum pair of flowers upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts spikelet filament non-flowering bract (scale) lodicule flowering bract (scale) • Each pair of flowers, together with a short stalk, forms a spikelet. • At the base of each spikelet is a pair of empty or nonflowering bracts. They protect the two flowers in the spikelet. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 35 Structure of Ischaemum muticum pair of flowers upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts spikelet filament non-flowering bract (scale) lodicule flowering bract (scale) • Spikelets also occur in pairs. The lower spikelet in each pair has no flower stalk, while the upper one is smaller and has a stalk. Both spikelets have similar structures. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 36 Structure of Ischaemum muticum pair of flowers upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts spikelet filament non-flowering bract (scale) lodicule flowering bract (scale) • Spikelets also occur in pairs. The lower spikelet in each pair has no flower stalk, while the upper one is smaller and has a stalk. Both spikelets have similar structures. • A few pairs of spikelets make up an inflorescence. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 37 Pollination in Ischaemum • By wind • Filaments protrude out of the bracts, exposing the anthers • With wind, dust-like pollen grains are shaken free • Stigmas also project out of the bracts. Feathery nature provide a large surface area to receive pollen grain that may be floating around Pollination in a Wind-pollinated Flower (Ischaemum muticum) upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) non-flowering bract (scale) • The mature stamens have long filaments that hang downwards and can swing freely. We say the filaments are pendulous. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 39 Pollination in a Wind-pollinated Flower (Ischaemum muticum) upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) non-flowering bract (scale) • The mature stamens have long filaments that hang downwards and can swing freely. We say the filaments are pendulous. • The filaments hang out of the bracts, exposing the mature anthers to the wind. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 40 Pollination in a Wind-pollinated Flower (Ischaemum muticum) pollen grains upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) non-flowering bract (scale) • When the filaments sway in the wind, the dust-like pollen is shaken free and carried away by the wind. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 41 Pollination in a Wind-pollinated Flower (Ischaemum muticum) upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) non-flowering bract (scale) • The mature stigmas do not hang freely but project out of the bracts. They are large, extended and feathery. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 42 Pollination in a Wind-pollinated Flower (Ischaemum muticum) pollen grains upper bisexual flower anther lower male flower feathery stigmas hanging out of the bracts filament lodicule flowering bract (scale) non-flowering bract (scale) • The mature stigmas do not hang freely but project out of the bracts. They are large, extended and feathery. • Thus, they provide a large surface area to receive any pollen that is floating around in the wind. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 18 July 2021 43 Characteristics of insect-pollinated and wind-pollinated flowers The differences in structure between insect-and wind-pollinated flowers Insect pollinated flowers are easily seen and often contain scent and nectar to attract the insects. The male parts are adapted so they make contact with the insect as it feeds from the flower. Wind pollinated flowers are often small and green with no scent. Male anthers protrude out from the flower to allow the wind to pick up the pollen and disperse it away from the plant. Male and female parts develop at different times. Examples of insect-pollinated flowers GZ Science Resources 2014 Examples of wind-pollinated flowers GZ Science Resources 2014
