flowers for moodle 2013 14
TRANSCRIPT
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
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)
Flower Anatomy
FilamentSta
men
Anther
Pistil
Style
Stigma
Petal
Ovary
Ovule
Receptacle
Sepal
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
Cross Pollination Methods• Wind Pollination
– Inefficient, high pollen production – Flowers (if present) are small and
not colorful
Cross Pollination Methods
• Vector pollination uses animals • More efficient • Plants attract pollinators by:
– Color– Fragrance– Nectar
Coevolution• Two species evolve in response
to changes in one another
Bee Pollination
Butterfly Pollination
Bat Pollination
Moth Pollination
Seed Dispersal• Wind scatters seeds
– Maple trees, dandelions
Barbs stick to animal fur– Burdock plant
Animals eat and excrete seeds
Fertilization
1. Pollen lands on stigma
2. Pollen tube grows in the style
3. Sperm and egg form a zygote
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)
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