Pollination In Plants Lecture 1 PDF

POLLINATION IN PLANTS PARTS OF A FLOWER Flower Part Form and Function Pedicel, Peduncle Flower stalk, Inflorescence stalk Receptacle Part of flower stalk bearing the floral organs, at base of flower. Sepal Leaf-like structures at flower base, protects young flower bud. Cal...

POLLINATION IN PLANTS PARTS OF A FLOWER Flower Part Form and Function Pedicel, Peduncle Flower stalk, Inflorescence stalk Receptacle Part of flower stalk bearing the floral organs, at base of flower. Sepal Leaf-like structures at flower base, protects young flower bud. Calyx All the sepals together are known as the calyx. Located above the sepals, some are large and colourful, sometimes scented, Petal sometimes producing nectar. Often serve to attract pollinators to the plant. Corolla All the petals together are known as the corolla. Stamen Male part of the flower, consisting of the anther and filament Filament The stalk which bears the anther and connects anther to the flower. Anther The pollen bearing portion of a stamen. Pollen A small circular structure containing male reproductive cells. Carpel\Pistil Female part of the flower. Consisting of the stigma, style and ovary. Stigma Top portion of the style and receptive surface for pollen grains which is often sticky. Style The stalk bearing the stigma connecting the stigma to the ovary. Enlarged lower portion of the style enclosing the ovule (s). The ovary matures to Ovary become a fruit. Ovule Located in the ovary. Carries female gametes. Ovules become seeds on fertilization. Filament The stalk which bears the anther and connects anther to the flower. Anther The pollen bearing portion of a stamen. Pollen A small circular structure containing male reproductive cells. Carpel\Pistil Female part of the flower. Consisting of the stigma, style and ovary. Stigma Top portion of the style and receptive surface for pollen grains which is often sticky. Style The stalk bearing the stigma connecting the stigma to the ovary. Enlarged lower portion of the style enclosing the ovule (s). The ovary matures to Ovary become a fruit. Ovule Located in the ovary. Carries female gametes. Ovules become seeds on fertilization.  Corolla Calyx protecting other floral parts when in a bud stage  The sex of a flower can be described in three ways: Staminate flowers: Flowers bearing only male sex parts. These are sometime referred to as "male flowers". Carpellate\Pistillate Flowers: Flowers bearing only female sex parts. These are sometimes referred to as "female flowers". Hermaphhroditic\Complete flowers: Flowers bearing both male and female sex parts. In many cases flowers are borne as a group on a common stalk, called an inflorescence. There are many different types of floral inflorescences. The type of inflorescence present is sometimes used to aid in classifying flowering plants.  POLLINATION IN PLANTS Angiosperms are highly evolved plants with well developed flowers and seeds enclosed within the fruits. The plants usually undergo sexual reproduction. The sexual reproduction initiates after the advent of pollination. Pollination is the process of transfer of pollen from the anthers of a flower to the stigma of the same flower (self pollination) or of another flower (cross pollination) of the same species. Pollination is a prerequisite for fertilization: the fusion of nuclei from the pollen grain with nuclei in the ovule. Fertilization allows the flower to develop seeds.  Most plants need help of pollinating agents in moving pollen from the stamens to the stigma of the carpel. Pollinating agents may be insects, birds, animals (mammals), wind and water that move pollen from the anthers to the stigmas of flowers, thus effecting pollination. E.g. bees, butterflies, hummingbirds, moths, some flies, some wasps, and nectar feeding bats. The flowers of these plants have peculiar characteristics which can help in successful pollination.  Insect Pollinated flowers Characteristic features of insect pollinated flowers: Flowers are brightly coloured and/or strongly scented Flowers have nectar glands which produce sugary nectar that attracts insects. Anthers are generally exerted out of the flower Pollen is deposited on the insect from the stamens when it visits the flower to collect or suck the nectar and is deposited on the stigma of the next flower of the same species the insect visits POLLINATION BY INSECTS Irregular shaped flowers pollinated by insects  Bird pollinated flowers Characteristic features of bird pollinated flowers: They often have colourful corolla, calyx, or stamens which are attractive to birds They are not often scented The petals are fused at the base to form a tube or cone known as corolla tube which allows penetration of the bird’s beak to collect nectar from base.  As the bird picks the nectar, it brushes against anthers picking up pollen on the beak and body. When the bird visits another flower of same species, the pollen gets deposited on the stigma of the second flower Stamens occur inside the corolla tube These types of flowers provide a large amount of nectar as reward for the bird pollinators POLLINATION BY BIRDS  Water pollinated flowers Characteristic features of water pollinated flowers: These plants are aquatic species The flowers release their pollen into the water which is passively carried to other flowers by water currents They produce a large number of pollens because most of them get lost by the flow of water. The pollen grains are often light in weight and have water proof coating  The stigmas are large and feathery to catch the pollens. In some species, the male flowers after maturation get detached from the mother plant and float above the water surface. The stalks of the pollinated flowers are usually very long to project their stigmas above the water surface to receive pollen from male flowers. The flowers need not to be colorful (no need to attract) and generally white in color POLLINATION BY WATER  Wind pollinated flowers Characteristic features of wind pollinated flowers: They produce huge amounts of non sticky pollen They often lack a large and showy calyx or corolla  They have many flowers packed into an inflorescence They have large stigmas They have large, well exposed anthers POLLINATION BY WIND  Mammal (animal) pollinated flowers Characteristic features of mammal (animal) pollinated flowers: They often have a strong scent e.g. those which attract mice have a yeasty odour The flowers are often relatively large in size  The petals fuse into a wide tube or cone-like shape which allows mouth parts of mammals like bats, mice to penetrate and suck the nectar situated at the base of the corolla tube They are quite sturdy in structure in order to bear the vigorous activity of the small mammals while they are feeding on the nectar They generally bloom during the night hours POLLINATION BY BATS