Reproduction in ANGIOSPERMS The flowering plants Overview of
- Slides: 32
Reproduction in ANGIOSPERMS The flowering plants
Overview of Role of flowers Flowers are developed from a series of modified leaves arranged in rings(whorls) p They emerge from buds p Flowers are reproductive structures p They are involved in Sexual reproduction p Some parts of a flower produce gametes p Fertilization occur within the flower p Part of the flower become a fruit in which embryos are stored until they are dispersed p
Flower structure The calyx, composed of individual sepals, surround and protects the flower bud. Dog rose Rosa canina
Most species of flowering plants are hermaphroditic; contain both male and female reproductive parts p However, many species have mechanisms to prevent self fertilization inorder to ensure greater genetic variation in offspring p
Flower consist of female parts p Carpel; comprising stigma, style and ovary containing ovules p Note: Although it isn’t a big deal, your text book uses the term Pistil incorrectly and this may cause confusion. The pistil is the entire female reproductive organ. Carpel is the term that refers to an ovary, style and stigma. In flowers where there is only one of these then the carpel=the pistil and the two terms and synonymous. However in flowers with more than one carpel the pistil refer to all the carpels together.
Flower structure Holds the ovules and after to Stalk connecting the stigma The top of the style; Receives fertilisation it develops into a the ovary. Holds the stigma in style + ovary the=stigma POLLEN + generally sticky or fruit to protect seed and a position thatthe facilitates in order to trap pollen grains aid in dispersal of the seed. pollination Stigma Ovule Style Carpel = pistil (in this case) Ovary Petal Anther Sepal Filament
Male Parts p Stamens; each comprising an anther (containing pollen) and a filament
stalk which supports Consists of pollen sacs the anthers and holds them a (typically 4), pollen grainsinare Male part of flower comprising positionhere. to facilitate dispersal formed These grains filament and anther pollen contain theof male gamete which if formed by meiosis. Flower structure Stigma Style Carpel = pistil (in this case) Ovary Petal Anther st n ame Sepal Filament
Parts that offer Protection or support p petals, sepal and receptacle
Flower structure Smallmain modified that are While Thickened role arealeaves isatattraction the top of usually green in colour (though of athe pollinator, stem from to where a degree the may be coloured and petalthey flower offer grows. protection It supports to rolethe like(petaloid)) and whose is stamens flower pistil to protectand the young flower bud Stigma Style Carpel = pistil (in this case) Ovary Petal Anther st n ame Sepal Filament Receptacle
Parts that attract pollinators (if applicable) Petal p Nectary p
Ovary position differs between flowers
Not all flowers are so simple Composite head of a daisy
p So this is actually a group of two different types of flowers
Pollination A Pollen grain contains the male gamete (2 nuclei/sperm cells) p Pollination is the transfer of pollen from anther to a receptive stigma p n p Pollination ≠ Fertilisation Pollen from a flower could land on the stigma of the same flower = self pollination
Pollination p Pollen transferred from the anther on one flower to the stigma of another flower on a different plant = cross pollination
Types of pollination ANIMAL BASED POLLINATION: an animal picks up pollen and transfer it to stigma of another flower Insect pollination Insect-pollinated flowers may have: • Brightly coloured petals • Strong sweet fragrance • Nectar producing glands • Guidelines to lead insects to Nectar a)
Mode of Pollination b) Bird pollination Bird-pollinated flowers may have: • Long tube shaped flowers • Bright red and yellow flowers • No odour c) Mammal pollination Animal -pollinated flowers may have: • White flowers • Strong fruity odour • Flowers opening at night
Animal Pollination p p Plants tend to specialise in pollinators This ensures the pollen is delivered to same species of plant Yellow archangel Lamiastrum galobdolon being pollinated by a bumble bee Bombus hortorum
Types of pollination 2. Wind Pollination: wind “picks up” pollen and carries it to stigma of another flower. Windpollinated flowers may have: • Large stigmas outside the flower • Little or no fragrance • Light non-sticky pollen
Fertilisation Pollination ≠ Fertilisation p The male gamete (the male nucleus) has to get to the egg cell p The egg cell lies in an ovule in an ovary at the centre of the plant p The pollen grain germinates on the stigma p It grows a pollen tube down the style p Its male nuclei travel down the pollen tube to the ovule p
Fertilisation Pollen grain Stigma Style Ovule Embryo sac Ovary © 2008 Paul Billiet ODWS Pollen tube
Fertilisation Embryo sac Polar nuclei Egg cell Micropyle © 2008 Paul Billiet ODWS
Fertilisation There are two haploid “sperm” cells in the pollen grain. p Double fertilization occurs p n n One “sperm” cell fuses with the egg to develop into diploid (2 N) embryo plant that becomes the seedling The other fuses with 2 other haploid cells in the ovule to form the endosperm(3 N); a tissue that provides nutrition to the embryo whilst waiting for seed germination.
The double fertilisation Ovule Nucellus Pollen tube Male nucleus + 2 polar nuclei = endosperm nucleus (3 n) Male nucleus + egg cell = zygote (2 n) © 2008 Paul Billiet ODWS Pollen tube entering micropyle
From flower to fruit Marsh marigold Caltha palustris © 2008 Paul Billiet ODWS
Fruits help disperse seeds To increase the chance of survival of a species, seeds need to be spread away from the parent plant to reduce competition for resources such as water, soil minerals and sunlight. p Plants invest energy in making fruits p Fruits assist with dispersing seeds p There are various mechanisms for seed/fruit dispersal p
Fruits and seed dispersal Animal dispersal Strawberry Fragaria vesca Explosive dispersal Bird’s foot trefoil Lotus corniculatus Animal dispersal Wood avens Geum urbanum Wind dispersal Ragwort Senecio © 2008 Paul Billiet ODWS
Dandelion
Stages of Strawberry developement
- Flowering and non flowering plants similarities
- What is classification of plant
- Classification
- Reproduction in flowering plants
- Seedless vascular plants vs bryophytes
- Polyembryony
- Multiple choice questions on flowering plants
- Algae mosses and ferns
- Male and female tulips
- Flowering plants are called?
- Cladogram of 5 indoor plants
- Ferns and conifers
- Flowering plants phylum
- øa section through a leaf
- Unit 2 lesson 10 seedless plants
- What are the main parts of flowering plants
- Plants and their functions
- Lesson 12 flowering plants
- Sexual reproduction and asexual reproduction
- Asexual vs sexual reproduction venn diagram
- Venn diagram of sexual and asexual reproduction
- Learning objectives of reproduction in plants
- Sexual and asexual reproduction in animals venn diagram
- Seed plants reproduction
- Learning objectives of reproduction in plants
- A sexual reproduction in plants
- Vegetative propagation examples
- Vascular vs nonvascular plants
- Male plant reproductive system
- Overview of plants
- Eudicot vs monocot
- Double fertilization in angiosperms
- Fascinating organ meaning