Sexual Reproduction in Plants

Sexual Reproduction in Plants

Sexual Reproduction includes:PollinationFertilizationSeed Production

Sexual reproduction also known as seed reproduction because it involves using seeds to produce new plants.SeedsSeeds contain all the genetic characteristics of the parent plantHowever, the characteristics of the plant grown from seeds may vary from parent plant.

Reasons for Seed PropagationMost EconomicalAllows a grower to produce a larger number of plants. Most widely used methodParts of the Flower

Parts of the FlowerStamen- Male reproductive part of the flowerAnther- produces the pollen grainsFilament- supports the anther.Pistil Female reproductive part of the flowerStigma- Sticky surface to capture the pollenStyle- Tube that connects the stigma to the ovaryOvary-contains the ovules. PollinationWhen a flower opens, the stamens mature and become fully developed.The anthers on the stamen then release hundreds of pollen grainsPollen grains are the male sex cellEach pollen grain contains genetic characteristics of the plant. PollinationFlower ovary contains one or more ovules, which are the female sex cellsEach ovule contains genetic information of the plant as well. Pollination occurs when the pollen grains come into contact with the sticky surface of the stigma.

Types of PollinationSelf Pollination:The transfer of pollen from the anther of a flower to the stigma of the same flower., or to a different flower on the same plant. Cross PollinationThe transfer of pollen from the anther of a flower to the stigma of a flower on a different plant.

Self PollinationMore EffectiveAlmost guarantees pollinationIsn't dependable on outside variables for pollinationCross PollinationIncreases genetic variabilityAccomplished through WindBeesBirds

Methods of Pollen DistributionWindPollen grains are carried by wind from one flower to anotherAnimalsBirds ( Hummingbirds)Insects ( moths, butterflies, bees, flies)Mammals ( bats) Flowers of wind pollinated plants are:Small Greenish or brownNo fragranceSmall or no petalsNo Nectar

Examples Include Grasses, wheat and cattails

Flowers that are pollinated by hummingbirds and butterflies are:Tube shapedFragrant fro butterflies, no fragrance for hummingbirdsBrightly colored, usually red attracts hummingbirdsProduce nectar which is an attractive snack.

Flowers that are pollinated by fliesBrown and dark coloredHave foul odor

Flowers that are pollinated by bees areFragrant (nectar as a reward)Brightly colored with nectar guides visibly only with UV light that bees can see, which directs bees to the center of the flowerSweet FragranceProduce Nectar

Flowers that are pollinated by bats and mothsTube ShapedFragrantWhite or yellow which can be seen easily at nightSometimes only open at night

FertilizationCells of many plant flowers are diploid ( two sets of chromosomes) Represented by 2nSome of these cells undergo a process of cell division called meiosis. This process causes the chromosomes number to be halved and the result are daughter cells. The daughter cells are haploid (one set of chromosomes) represented by 1nFertilization The daughter cells undergo another process of cell division called mitosis, which produce more haploid egg or sperm cells. When these cells come together (fertilization) they form the zygote which is then a diploid

Process of fertilizationAfter the pollen grain lands on the stigma, it develops a pollen tube which travels down the style. The pollen grain releases a sperm cell, in some cases 2 sperm cellsThe sperm travel down the pollen tube and reach the ovary, then enter the ovuleIf there are two sperm cells, one fertilizes the egg while the other fuses with another cell and produces the endosperm. This is called double fertilization. Development of SeedThe diploid zygote forms the embryo. These cells will later divide and form parts of the seedCells in the outer layer of the ovule harden and become the seed coat.The endosperm grows and becomes the food source for the growing seed

3 essential parts of the seed. Embryo- Embryonic Root (Radical)Endosperm/Cotyledon- Food ReserveSeed Coat