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Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
The stamens are the male organs and produce pollen that contain the male gametes
The pistil with the stigma, style and ovary is the female organ of the plant. The ovulums are found in the ovule.
Lorraine Kuun, July 2011
Stamens consist of an anther with a filament.
The anther produces pollen in the pollen sac.
The pollen grains contain the male gametes.
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
1. Self pollination 2. Geitonogamy 3.Cross-pollination
Lorraine Kuun, July 2011
Most pollinators are insects e.g. Bees, moths, butterflies, beetles.
Some vertebrates also pollinate flowers e.g. Bats, mice, birds (mainly).
Many flowers are pollinated by wind.
Lorraine Kuun, July 2011
Bright colours (bees cannot see red), white for night pollinators e.g. moths
Often sweet scent (attracts moths and butterflies)
Reward of nectar and pollen Contrasting markings on petals to locate
centre of flower (usually not visible to human eye – ultraviolet)
Pollen cling to hair on insect bodies
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Landing platform
Nectar guides
Tubular shape, contains nectar
Stamens form “lever”
Pistil overhanging landing platform
Bees attracted to blue and yellow flowers
High yield of dilute nectar Bigger than most insect-pollinated flowers Open in daytime, often red Sturdy against rough feeding of birds Little or no scent – birds have poor sense of
smell Protect ovary against beaks by being
inferior or by partition Pollen sticks together in clumps Often erect or with landing platform for
birds that do not hover
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Bright colours
Nectaries
Sturdy landing platform
Stigma close to pollen
Stamens fused in tube to fit beak
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Flowers do not have scent, nectar or brightly coloured petals – no need to attract pollinators.
Flowers high on plant to be exposed to wind. Flowers usually small and reduced, lacking
calyx or corolla (sepals and petals). Anthers large and well-exposed. Masses of light, non-sticky pollen produced. Stigmas long and feathery with large area
for trapping pollen.
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Meiosis occurs in the pollen grain.
The male gametes are haploid.
When the ripe pollen grain lands on a receptive stigma, it will germinate.
The pollen grain germinates and form a pollen tube.
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
The ovary contains the ovule(s) with female gametes (n).
The pollen tube grows down the style, through the micropyle and into the embryo sac.
Double fertilisation occurs.
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
The fruit develops from the following layers:
• Fruit wall from ovary wall.
• Seed from ovule.
Lorraine Kuun, July 2011
A seed consists of a
1. Seed coat – outer layer of ovule (pericarp).
2. Embryo – from fertilisized egg cell (zygote undergoes mitosis).
Lorraine Kuun, July 2011
Endosperm – result of double fertilization. Endosperm is food for embryo – also why we eat seeds for food.
Lorraine Kuun, July 2011
The cotyledons contain food for the embryo in some seeds.
In beans the cotyledons are responsible for photosynthesis after germination before first leaves are formed.
Lorraine Kuun, July 2011
MONOCOTYLEDON
Lorraine Kuun, July 2011
DICOTYLEDON
Lorraine Kuun, July 2011
Resistant to unfavourable conditions as they have seed coat.
Can be dispersed effectively (see later). Can remain viable in dormant state for long
periods. Seeds have stored food reserve in
endosperm or cotyledons; includes starch, oils and or protein.
Important to man as they are cheap form of plant propagation, way to store plants and are a store of food.
Lorraine Kuun, July 2011
Dormancy is a state of rest. Embryo inactive, seed will not germinate.
Some plants have obligatory period of dormancy – seed will not germinate even if conditions are favourable.
Dormancy prevents seeds from hatching in wrong season when seedlings would be exposed to unfavourable conditions. Allows seeds to survive unfavourable conditions.
Allows for seed dispersal agents to act.
Lorraine Kuun, July 2011
Wind – seeds are light with plumes or wings.
Animals – hooks and thorns – cling to wool, stick in paws.
Animals – edible fruit – seeds egested in different position.
Water – seeds contain oil or air bubbles – float away.
Self-dispersed – fruit dry, dehiscent.
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
COCO DE MER drifts along ocean currents
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
Most important plant source of food for humans.
Practical form of food – easy to transport and store for long periods of time.
Grains – wheat, maize (mealies), sorghum, rice, oats; mainly starch
Pulses (legumes) – beans, peas, soy beans, peanuts, lentils, plant proteins
Nuts – oily seeds in hard shells e.g. walnuts, cashews, pecans etc.
Lorraine Kuun, July 2011
Many plant species under threat. Seed bank stores seeds of wild plants and crops. UK – conserves seeds of about 10% of wild plant
species at Kew – Millennium Seed Bank Project. Swedish International Seed Vault – reinforced
concrete tunnel – 4,5 million seed samples – will remain viable for 1000’s of years.
MSBP working with SA National Biodiversity Institute – contributing 2500 indigenous species – endangered, endemic, over-exploited
Lorraine Kuun, July 2011
Offer protection against loss of species in wild due to:
1.Habitat loss – agriculture, development of cities, building of dams, large-scale ecological disasters etc.
2.Climate change3.Over-exploitation of certain species
Lorraine Kuun, July 2011
Can be used to 1. re-establish damaged, lost
habitats and ecosystems2. re-introduce extinct,
endangered or threatened species
3. provide research material
Lorraine Kuun, July 2011
Lorraine Kuun, July 2011
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