Download Plant Reproduction Angiosperm specific adaptations Angiosperms

4/15/2013
Gymnosperms
Pterophytes
Plant Reproduction
Angiosperms
Seeds
Lycophytes
Bryophytes
Vascular tissue
BI 103 Plant-Animal A&P
Turn in Homework #1
Green algae:
Chlorophytes
Land plants
Angiosperm specific adaptations
• Unlike other plants they have:
– Flowers
– Double fertilization
– Fruit
Angiosperms: the Flowering plants
Why do plants have flowers? In
other words, what are the
advantages of flowering?
Discuss this question in groups
Alternating Generations
In more advanced plants, the sporophyte generation is
dominant.
Why do plants have flowers?
Enlists partnerships with insects and
other animals
Less inbreeding
Higher probability the pollen will reach
the right plant
They don’t have to produce as much
pollen
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Alternation of generations modified
• Pollen= Male gametophyte
Contains sperm
How is pollen an adaptation to land?
Allows fertilization to occur even in the absence
of available water.
• Ovule= Female gametophyte
water
Contains egg
Moss fertilization
Pollen grains
Anthers with microspores
Microspore to pollen
1. The microspores divides by mitosis
to produce two cells
Generative cell (1n)
Tube cell== vegetative nucleus (1n)
2. A two layered wall develops around
the microspore to become the
pollen
3. The generative cell undergoes
division once more
 3n total (3 nuclei) in pollen
Double fertilization
Fruit development
1. Two pollen nuclei enter ovule
2. One fuses with the egg to form the zygote
3. The other fuses with 2 central cell nuclei to become the
endosperm (3n), food for the zygote
Becomes the seed!
Becomes the fruit!
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Why do we see such diversity in the
flowers we see?
Theory: Coevolution of plants and pollinators
Different flowers have evolved to attract different
pollinators- plants have specialized to a specific
group of pollinators
Pollination syndrome
Floral characteristics which attract a specific
group of pollinator
Bees, hummingbirds, moths etc
Allows flowers to specialize
May include mechanisms to exclude other
pollinators
Pollination syndrome
What are the advantages to specializing to one
species or one group of pollinator?
What are the disadvantage or risks?
Most flowers are ‘generalists’ and do not
specialize.
Bees
Blue
Symmetrical
Smells sweet
Pollen
rewards
Nectar
rewards
Pheromone
rewards
Bees
UV Markings
 Bees can see in UV!
Pollinators: Bees
 Blue
 UV marking
Symmetrical
Smells sweet
Nectar guides ---Example: Catalpa speciaosa
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Bee specialization
Pedicularis
attollens, common
name:“Baby
Elephant’s head”
Bumble bee
pollinated
Pedicularis
attollens
Specialized
Buzz pollination
Technique only used by bees to release pollen
from anthers– they must hit the right musical
note!
Birds: hummingbirds
Red
Long and tubular
 No odor
nectar
Example: Tomatoes, blueberries, manzanita
(Arctrostaphylos)
https://www.youtube.com/watch?v=Nv_xncrZ
fCg&feature=related
Moths
White flowers
Sweet smell
Open at night
Long nectar
spur with
nectar
Moths
Darwin’s Orchid, Angraecum sesquipedale
Hawkmoth on Columbine (Aquileia)
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Why are those spurs so long?
Predator: Crab spider
Combination of:
Moths don’t want to get too close….
Predators lurk!
Plant needs moth to get close enough to
reach pollen and stigma
Bats
Strong pedicle and petals
Musky odor
White
Open at night & lots of pollen
Ex: Sargo cactus
Flies: rancid smell, tiny, green or
reddish
Butterflies
Sweet smell
Vibrant colors
Larger flowers
Nectar rewards
Announcements
• Homework #2 Design a flower --Due next
Monday 4/22
• Lab report– due Wed in lab
• Outdoor lab section?
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