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Plant Reproduction
Structure of a Flower
Male Reproductive Structure
The stamen consists of
two parts: Anther and
Filament
The anther is where
meiosis occurs to
produce haploid pollen
The filament is a stalk
that supports the
anther
Female Reproductive Structure
The pistil consists of
the stigma, style and
ovary
The sticky stigma
receives the pollen
from the anther
The pollen grows a
tube down through the
style
Meiosis occurs in the
ovary to produce
haploid ovules
Accessory Structures
The calyx consists of
all the sepals, which
protects the flower
before it opens
The corolla consists of
all the petals, which
serve to attract
pollinators through
color and scent
Pollination
Wind, insects or other
animals transfer pollen
from the anther of one
flower to the stigma of
another
Flowers vary
depending on
pollination mechanism
Pollination Animation
Pollination Vectors
Wind Pollination: Dull, scentless
flowers with reduced petals
Bees/Butterfly Pollination: Bright
color, nectaries, scent.
They sip nectar, get pollen on coats,
transfer pollen from flower to flower
Bird Pollination: Nectaries, bright
colors, tube-like flowers
Moth Pollination: White petals,
open at night
Fly Pollination:Rank odor, flesh
colored petals
Double Fertilization
Fertilization
After pollen lands on stigma, a pollen tube
grows down through the style to ovary
Tube contains two sperm nuclei
In ovary, there is one egg or ovule nucleus
and two polar nuclei
Double fertilization occurs: one sperm
nucleus fertilizes the egg, the other the two
polar nuclei
Result of Double Fertilization
The sperm nucleus and egg nucleus join to
form a 2n (diploid) embryo
The other sperm nucleus and the two polar
nuclei join to form a 3n (triploid)
endosperm. The endosperm is the food
supply for the embryo.
Fruit Development
Seed and Fruit Development
After fertilization,
the petals and
sepals fall off
flower
Ovary “ripens”
into a fruit
The ovule
develops into a
seed
Ovary
Seed Dispersal MechanismsAllow plants to colonize new areas and avoid
shade of parent plant
Wind Dispersal - Flight mechanisms,
like parachutes, wings, etc.
Ex. Dandelion, maples, birch
Animal Dispersal - Fleshy fruits which
animals eat, drop undigested seeds in
feces or burrs which stick to
animals’ coats
Gravity Dispersal Heavy nuts fall to
ground and roll
ex. acorns
Water Dispersal - Plants
near water create floating
fruits
ex. coconuts
Monocot Seed Germination
Monocots grow
straight up with
coleoptile sheath
covering shoot
One embryonic leaf
Seed remains
underground
Dicot Seed Germination
Curved stem comes up
out of soil
Two embryonic leaves
Seed goes above soil
Parts of the Embryo
Epicotyl - Grows into
the leaves of the plant
Hypocotyl - Becomes
the stem
Radicle - Becomes the
root