Download BIO509 Lecture # 20 File

School of Sciences, Lautoka Campus
BIO509 Botany Lecture 20:Pollen
ecology of angiosperms
Photo courtesy of Prof. Randy Thaman
Learning outcomes
• Know the similarities and difference between
angiosperms and gymnosperms.
• Understand the major trends of specializations in
flowering plants
• Know the reproductive structures and lifecycle of a
flowering plant.
• Know the characteristics of flowers associated with
specific types of pollinators.
Pollination Ecology
What is pollination?
Pollination: The transfer of pollen from the
male anther to the female stigma.
Why is pollination important?
• Allows plants directed mobility in
seeking a mate.
• Cross-fertilization at high frequency.
• Sexual reproduction is advantageous to
an organism only if it happens with
someone other than itself.
How do plants get pollen from one plant to
another?
•
•
•
•
•
•
•
•
•
Bees
Beetles
Butterflies
Moths
Birds
Flies
Bats
Wind
Water
Reproductive floral organs: female
• Carpel or pistil – female reproductive organs; contains:
Stigma – is where pollen sticks to
Style – is the long tube that connects stigma to ovary
Ovary – enlarged structure at the base of carpel/pistil
where the ovules are located; it will become the fruit.
Ovules – contains female
gametophyte, becomes
the seed
carpel
or
pistil
ovary
Reproductive floral organs: male
• Stamen – male floral organ, consists of:
Anther – part of the stamen that produces pollen
Filament – stalk-like structure that holds anther
Pollen – immature male gametophyte
Non-reproductive floral organs
• Corolla – whorl of petals in a
flower.
• Petals – whorl of flower organs
that are often brightly colored to
attract pollinators. (units of
Corolla).
• Calyx – whorl of sepals in a flower.
• Sepals – whorl of leaf-like organs
outside the corolla; help protect
the unopened flower bud (units of
calyx).
Function of flower
• To attract pollinators with colorful petals, scent,
nectar and pollen.
Plant-pollinator relationships have evolved
together.
• Flowers and insects have coevolved.
• Angiosperm evolution has contributed to insect
diversity.
• In some cases relationship between pollinators and
flowers have become specialized.
Animal/ insect-flowering plant interaction is a
classic example of co-evolution
• Plants evolved elaborate
methods to attract animal
and insect pollinators.
• Pollinators evolved
specialized body parts and
behaviors that aid plant
pollination.
special structures on legs of a bee help to get more pollen.
http://www.cyberbee.net/biology/ch3/thorax.html
Animal/ insect Pollination as Mutualism
• Usually viewed as mutualism (where
both species benefit).
–Plant gets pollen transferred.
–Animals and insects get “rewards”.
Rewards
• Pollen is high in protein.
• Also has lipids, minerals,
starch.
• Nectar - sugary fluid produced
by nectar glands (nectaries) in
flower.
• Some flowers may have amino
acids too. (butterfly flowers).
Rewards are renewable
Floral nectaries are usually
located at the base of the flower.
Lets look at some special
modifications of flowers that
came about during the course of
their evolution in response to
specific pollinators.
Bee pollinated flowers
• Bees are the most important group of flower
pollinators.
– intelligent, lively insects.
– visual insects, have good eyesight (including UV
light).
– good smellers (good sense of smell).
– active during the day.
– they live on the nectar and feed
larvae, also eat the pollen.
Bee pollinated flowers
• Bees prefer blue and yellow, but rarely red
(appears black).
• Some flowers have honey guides, sometimes
visible only in UV light.
• Flowers have bee landing platforms.
• Flowers produce nectar and pollen to attract
bees.
• Many are sweet and fragrant.
• Some evolutionary more advanced flowers
particularly orchids have developed complex
mechanisms that force bees to visit them.
- complex passage ways.
- sexual mimicry – pseudo-copulation
Ophrys an orchid species mimics
female wasps
A male wasp “mating” with an Ophrys
flower (how embarrassing...)
Beetle pollinated flowers
• Beetles are one of the common pollinators.
• Beetles are:
– Clumsy
– Have poor vision
– Active during the day (many flower-visiting
ones).
– Derive nutrition from flower nectar, petals
and fruits.
Beetle pollinated flowers
• Relatively large or grouped into large
inflorescences.
• Light or dull colored .
• Have strong odor (fruity or spicy smell).
• Flowers often have inferior ovaries.
Moth and butterfly pollinated flowers
• Butterflies and moths have
- Good vision
- Good sense of smell
- Long coiled tongue.
- Must land on flower to visit it (can’t hover).
Moth and butterfly pollinated flowers
• Butterfly pollinated
flowers are brightly
colored, blue,
yellow, and orange,
and sometimes red.
• Yellow and white
flowers appeal to
night-flying moths.
Sweet fragrances.
Landing platform
present.
Often have nectar at
bottom of long floral
tube or spur usually only
accessible only to long
sucking mouthparts of
moths and butterflies.
Bird pollinated flowers
• Birds are regular visitors to flowers.
• have a good sense of color, they like yellow or
red flowers.
• Do not have a good sense of smell
• Feed on fluid nectar in greater quantities than
insects, usually have long beaks.
• Active during the day.
• Can hover (humming birds)
Bird pollinated flowers
• Flowers are usually
red or orange.
• Odor less flowers.
• have nectar hidden by
long floral tube
• no landing platform
Large and on tree
trunk or in large
inflorescences.
Birds prefer copious
amounts of nectar
since energy
needed.
Pollen sticks to the
feathers around their
bill.
Fly pollinated flower
• Flies have good
sense of smell,
especially flesh flies.
• Attracted to rotting
meat (lay eggs in
meat, larvae are
maggots).
Fly pollinated flowers
• Smell like rotting meat.
• Look like rotting meat (dark red, purple)
• Offer no reward: flies fooled by flower.
Stapelia flower
Rafflesia flower
Did you know?
• World’s largest known flower is
pollinated by flies.
• Rafflesia arnoldii from
genus Rafflesia is the largest
individual flower on earth.
• Has a diameter of about 1m and can
weigh about 11 kg.
• Has a strong odor of decaying flesh
and is commonly known as the
"corpse flower".
• It is an endemic plant that occurs
only in the rainforest of Indonesia
and Malaysia.
Bat pollinated flowers
• Bats are flying mammals.
• Flower visiting bats are usually
found in tropical areas.
• Eyesight good but echolocate.
• Good sense of smell.
• Active during night (nocturnal).
• Can hover when visiting flower.
• Have long extensible tongues
sometimes with brush like tip.
Bat pollinated flowers
• Flowers are open at
night.
• Lots of pollen and nectar
as rewards.
• White or light-colored.
• Large or in ball-like
inflorescence.
• Fragrant (sweet).
Bat Pollinated Flowers
May be
pendant
(hang from
branches).
Pendent
flower
What are the benefits of
animal/ insect mediated
pollination?
Mutualism Exceptions
• Some flowering plants are wind pollinated.
• Some are water pollinated.
Betula papyrifera – wind pollinated
Vallisneria – water pollinated
Wind pollinated flowers
• Primary mode of
pollination in grasses,
sedges, etc.
• Flowers are small,
grouped together.
• Flowers greenish (not
colourful).
Usually large
amounts of pollen
is produced.
Stamens often
protruding and
stigma sticky.
Not a very
efficient method
(too chancy and
wasteful)
Water pollinated flowers
• Submerged angiosperms.
• Pollen is transported
underwater or floats.
• In some cases, pollen are
thread like.
The shape and form of pollen is related to its
method of pollination
• Insect-pollinated species
have sticky of barbed
pollen grains
• Wind-pollinated species
is lightweight, small and
smooth (corn pollen)
What would be the
consequences if animal and
insect pollinators went extinct?
Readings
Chapter 23
Stern’s Introduction to Plant Biology
Chapter 22
Biology of Plants.
Questions??