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

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

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

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

Flower structure Dog rose Rosa canina © 2008 Paul Billiet ODWS

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

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

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

Pollination The honey bee Apis melifera on marsh thistle Cirsium palustris © 2008 Paul Billiet ODWS

Pollination Some flowers are highly specialised to encourage only one type of insect Fox glove flowers Digitalis purpurea © 2008 Paul Billiet ODWS

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

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

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

Fertilisation Embryo sac Polar nuclei Egg cell Micropyle © 2008 Paul Billiet ODWS

Fertilisation Pollen grains of the daisy Bellis perennis © 2008 Paul Billiet ODWS

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

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

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

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