1. Flowers
• Reproductive structures of angiosperms
• Sepals are the outermost layer which
encloses a bud and protects the
developing flower
• Petals are just inside sepals, fragrance
and color attracts pollinators
• The receptacle is where sepals,
petals, and sex organs attach

2. Flowers (cont.)
• Stamen - male sex organ
– Anthers produce pollen
– Filaments hold the anther up for
pollinators or wind
• Pistil (aka carpel) – female sex organ
– The stigma is the sticky end where
pollen lands
– The style is the “neck” which connects
the stigma to the ovary
– The ovary contains ovules, when
mature the ovary becomes a fruit (ovules
become seeds)

3. Flower Anatomy
Petal
m
ta Anther
S
Filament
til
Pis
Stigma
en
Style
Ovary
Ovule
Receptacle
Sepal

4. Pollination
• Pollen transfers from anther to stigma
– Self-pollination – pollen fertilizes ovule
of the same plant
– Cross-pollination – pollen fertilizes
ovules of another plant
• thus increasing genetic variation

5. Cross Pollination Methods
• Wind Pollination
– Inefficient, high pollen production
– Flowers (if present) are small and not
colorful

6. Cross Pollination Methods
• Vector pollination uses animals
• More efficient
• Plants attract pollinators by:
– Color
– Fragrance
– Nectar

7. Coevolution
• Two species evolve in response to
changes in one another

8. Bee
Pollination

9. Butterfly
Pollination

10. Bat
Pollination

11. Moth
Pollination

12. Seed Dispersal
• Wind scatters seeds
– Maple trees,
dandelions

Barbs stick to animal fur
– Burdock plant

Animals eat and excrete seeds

13. Fertilization
1. Pollen lands on
stigma
2. Pollen tube grows
in the style
3. Sperm and egg
form a zygote

14. Double Fertilization
• 2 sperm enter the ovary
• 1st sperm fertilizes the egg;
results in a zygote (2N)
• 2nd sperm fertilizes the polar
nuclei; forms endosperm (3N)
http://bcs.whfreeman.com/thelifewire/content/chp39
/3902001.html