Reproduction in Flowering Plants

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Transcript Reproduction in Flowering Plants

Reproduction in Flowering Plants
Mrs. Zemcik
Living Environment
Expanded by
Joe Naumann, UMSL
Emphasis on Pollinators
Flower
• Sexual reproductive structure
• Produces egg and sperm
• Fertilization takes place inside
the flower
Female
reproductive
organ
Pistil
*Stigma –top of the pistil,
Sticky surface for pollen to
stick to
*Style – connects the stigma
to the ovary
*Ovary –contains ovules
( eggs)
Male
reproductive
organ
Stamen
*Anther – produces sperm
nuclei by meiosis. Sperm
nuclei are enclosed by
pollen grains.
*Filament – holds the anther
up
Pollination
• Transfer of mature pollen grains from the
anther to the stigma
-wind
-insects
-birds & other animals
Important (endangered?) Pollinators
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Bees
Butterflies
Moths
Wasps
Bombyliid flies
syrphid flies
Beetles
Midges
Thrips
Ants
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Green bottle flies
Bactrocera fruit flies
Bats
Birds
– Hummingbirds
– Honeyeaters
– Sunbirds
• monkeys, lemurs,
possums, rodents and
lizards
Scopa (pollen holder) of a
Megachilid bee
Halictid bee, showing adhering
pollen
Syrphid fly,
showing
some
adhering
pollen
Halictid bee
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.
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.
• When a pollen grain lands on the
stigma, it germinates and a pollen tube
grows down through the style to an
ovule (egg)
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)
*Self pollination –pollen from same flower
*Cross pollination – pollen from a different flower
- more variation
• 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
The plant embryo uses food stored in the
cotyledon of the seed until it develops
leaves for photosynthesis
Seedling
micropyle –opening in ovule where pollen tube attached,
sperm entered
hilum –scar where ovule attached to ovary
radicle –embryonic root
Epicotyl – grows above the cotyledons and gives
rise to the leaves.
Hypocotyl –below the point of attachment of the
cotyledon, develops into the stem.
Parts of a seed
• Dicot
Seed coat
Hypocotyl
Epicotyl
Cotyledons
Endosperm
• Monocot
Seed coat
Epicotyl
Hypocotyl
Cotyledon
Radicle
Seed Germination
Monocot
Dicot
Epigeous
Hypogeous
Radicle
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