1. ANGIOSPERMS The flowering plants Spring crocus Crocus vernus
© 2008 Paul Billiet ODWS
Spring crocus Crocus vernus

2. Flower structure Flowers are reproductive structures
The have evolved to send and receive pollen from one flower to another
This is process of pollination
Flowers are developed from a series of modified leaves
These leaves are arranged in a rings (whorls)
© 2008 Paul Billiet ODWS

3. Types of pollination Wind Animal Water
Bumble bee Bombus hortorum on red clover Trifolium pratense
Yorkshire fog grass Holcus lanatus
© 2008 Paul Billiet ODWS

4. Animal pollination Usually insects Also other flying animals
e.g. hummingbirds or fruit bats
Cerambycid beetle pollinating bramble Rubus fruticosus
© 2008 Paul Billiet ODWS

5. Flower structure
Dog rose Rosa canina
© 2008 Paul Billiet ODWS

6. Flower structure Stigma Style Ovary Petal Anther Sepal Filament
© 2008 Paul Billiet ODWS

7. Pollination Pollen grains contain the male gametes of the plant
Yellow archangel Lamiastrum galobdolon being pollinated by a bumble bee Bombus hortorum
Pollen grains contain the male gametes of the plant
They are picked up by a pollinator and transferred to another flower
Plants tend to specialise in pollinators
This ensures the pollen is delivered to same species of plant
© 2008 Paul Billiet ODWS

8. Pollination
Small skipper Thymelicus flavus on marsh thistle Cirsium palustris
© 2008 Paul Billiet ODWS

9. Pollination
The honey bee Apis melifera on marsh thistle Cirsium palustris
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10. Pollination
Some flowers are highly specialised to encourage only one type of insect
Fox glove flowers Digitalis purpurea
© 2008 Paul Billiet ODWS

11. Pollination Most species of flowering plants are hermaphroditic
Pollen from a flower could land on the stigma of the same flower or another flower on the same plant = self pollination
Pollen transferred from the anther on one flower to the stigma of another flower on a different plant = cross pollination
© 2008 Paul Billiet ODWS

12. Fertilisation Pollination ≠ Fertilisation
The male gamete (the male nucleus) has to get to the egg cell
The egg cell lies in an ovule in an ovary at the centre of the plant
The pollen grain germinates on the stigma
It grows a pollen tube down the style
It male nuclei travel down the pollen tube to the ovule
© 2008 Paul Billiet ODWS

13. Fertilisation Pollen grain Stigma Style Ovule Embryo sac Ovary
Pollen tube
Ovary
© 2008 Paul Billiet ODWS

14. Fertilisation Embryo sac Polar nuclei Egg cell Micropyle
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15. Fertilisation Pollen grains of the daisy Bellis perennis
© 2008 Paul Billiet ODWS

16. Fertilisation
Germinating pollen grains of blue bell, Hyacinthoides non-scripta
© 2008 Paul Billiet ODWS

17. The double fertilisation
Pollen tube
Pollen tube entering micropyle
Male nucleus + egg cell
= zygote (2n)
Male nucleus + 2 polar nuclei = endosperm nucleus (3n)
Ovule
Nucellus
© 2008 Paul Billiet ODWS

18. From flower to fruit Marsh marigold Caltha palustris
© 2008 Paul Billiet ODWS

19. 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