This document summarizes the sexual reproduction process in flowering plants. It describes the structures of flowers including pistils and stamens, which contain the female and male reproductive organs. Pollination is explained as the transfer of pollen grains between flowers by wind, insects, birds or other animals. Many species of pollinators are listed, and their declining populations are identified as a serious threat due to their critical role in crop pollination and food webs. The full fertilization and seed development process is then outlined, from pollen tube growth and fertilization to seed and seedling formation.

1. Reproduction in Flowering Plants
Emphasis on Pollinators
Mrs. Zemcik
Living Environment
Expanded by
Joe Naumann, UMSL

2. Flower
• Sexual reproductive structure
• Produces egg and sperm
• Fertilization takes place inside
the flower

3. Pistil
*Stigma –top of the pistil,
Sticky surface for pollen to
stick to
*Style – connects the stigma
to the ovary
*Ovary –contains ovules
( eggs)
Stamen
*Anther – produces sperm
nuclei by meiosis. Sperm
nuclei are enclosed by
pollen grains.
*Filament – holds the anther
up
Female
reproductive
organ
Male
reproductive
organ

4. Pollination
• Transfer of mature pollen grains from the
anther to the stigma
-wind
-insects
-birds & other animals

6. Important (endangered?) Pollinators
• Bees
• Butterflies
• Moths
• Wasps
• Bombyliid flies
• syrphid flies
• Beetles
• Midges
• Thrips
• Ants
• Green bottle flies
• Bactrocera fruit flies
• Bats
• Birds
– Hummingbirds
– Honeyeaters
– Sunbirds
• monkeys, lemurs,
possums, rodents and
lizards

9. Scopa (pollen holder) of a
Megachilid bee

10. Halictid bee, showing adhering
pollen

11. Syrphid fly,
showing
some
adhering
pollen

12. Halictid bee

17. Pollinator population declines
and conservation
• In 1999 the Convention on Biological Diversity
issued the São Paulo Declaration on
Pollinators, recognizing the critical role that
these species play in supporting and
maintaining terrestrial productivity as well as the
survival challenges they face due to
anthropogenic change. Today pollinators are
considered to be in a state of decline; some
species, such as Franklin’s bumble bee
(Bombus franklini) have been red-listed and are
in danger of extinction.

18. Serious Problem
• Declines in the health and population of
pollinators pose what could be a
significant threat to the integrity of
biodiversity, to global food webs, and to
human health. At least 80% of our world's
crop species require pollination to set
seed. An estimated one out of every three
bites of food comes to us through the work
of animal pollinators.

19. • When a pollen grain lands on the
stigma, it germinates and a pollen tube
grows down through the style to an
ovule (egg)

20. Fertilization
• The sperm travels through the pollen tube to the
ovule. The sperm & egg fuse forming the zygote
(fertilized egg) –this grows into the plant embryo
(cells grow by mitosis)

21. *Self pollination –pollen from same flower
*Cross pollination – pollen from a different flower
- more variation

22. • The ovary and zygote (fertilized ovule)
develop and ripen.
*The ovule forms the seed and the ovary
forms the fruit.
• A fruit is a ripened ovary

23. The plant embryo uses food stored in the
cotyledon of the seed until it develops
leaves for photosynthesis

24. micropyle –opening in ovule where pollen tube attached,
sperm entered
hilum –scar where ovule attached to ovary
radicle –embryonic root
Seedling

25. Epicotyl – grows above the cotyledons and gives
rise to the leaves.
Hypocotyl –below the point of attachment of the
cotyledon, develops into the stem.

26. Parts of a seed
• Dicot
• Monocot
Seed coat
Epicotyl
Cotyledons
Hypocotyl
Seed coat
Endosperm
Epicotyl
Hypocotyl
Radicle
Cotyledon

27. Seed Germination
Monocot Dicot
Hypogeous
Epigeous
Radicle

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