Introduction to Plant
Reproduction
23.1
Reproduction
Sexual
reproduction
–Joining of an egg and sperm
Asexual
reproduction
–A single organism replicating its
genetic material to split into two
identical organisms.
Vegitative Reproduction
A form of asexual reproduction where
a new plant grows from parts of an
existing plant.
Fast reproduction
Examples:
– Strawberry runners
– Moss fragmentation
– Potato eyes and buds
Alteration of Generations
Alteration of Generations
Of Nonseed Nonvascular Plants
Alteration of Generations
Of Nonseed Vascular Plants
Alteration of Generations
Of Naked Seed Vascular Plants
Alteration of Generations
Of Flowering Seed Vascular
Plants
Alteration of Generations
Fertilization:
Nonvascular plants- Need a film of
water for the sperm to reach the
egg.
Vascular
plants- Do not need
water for the sperm to reach the
egg.
Alteration of Generations
As plants evolved, the sporophyte
generation became larger:
Nonvascular plants- Sporophyte
depends on the gametophyte for
support and nutrition.
Vascular
plants- Sporophyte lives
independent of the gametophyte.
Moss reproductive
cycle
Gametophyte dominant
– Male= Antheridium
– Female= Archegonium
Antheridium
Archegonium
Moss reproductive
cycle
Antheridium- Male produces
flagellated sperm that need water to
get to the archegonium.
Chemotaxis- Female archegonium
produces chemicals that attract/direct
the sperm.
Moss reproductive
cycle
Moss reproductive
cycle
Sporophyte- Depends on the
gametophyte for support and
nutrition.
Protonema- Spores that land in a
favorable spot develop into a
protonema (gametophyte
generation).
Fern reproductive cycle
Sporophyte dominant
Frond- feathery stems of a fern
Sorus- underneath the frond
–Produces spores
Fern reproductive cycle
Prothallus
– The fern spore grows into a
prothallus when it lands on damp,
rich soil.
– Heart shaped
– Contains Antheridia
& Archegonium
Conifer reproductive
cycle
Sporophyte dominant
Heterosporous- Produces two kinds
of spores that develop into male and
female cones.
– Female cones
–Made of many scales
–2 ovules at the base of each scale
–Each ovule produces a
Megaspore which develops into
the female archegonia.
Conifer reproductive
cycle
– Male cones
–Made of small scales that form
microspores
–4 microspores develop into a
single pollen grain
–Pollen grains are the
male gametophyte that
are transported on air
currents
Chapter 23.2
Flowers
The Parts of a Flower
• Most flowers have
four parts:
• sepals,
• petals,
• stamens,
• Carpels
(pistils)
The parts of a flower
• Sepals protect the
bud until it opens.
• Petals attract
insects.
• Stamens make
pollen.
• Pistils (carpel) grow
into fruits which
contain the seeds.
Stamen (male)
• Anther: pollen
grains grow in the
anther.
• When the grains
are fully grown, the
anther splits open.
• Filament: holds the
anther
Pistil (female)
• Stigma
• Style
• Ovary
Stigma – sticky place for
pollen to attach
Style – where pollen nuclei
travels to reach the egg
Ovary – where egg is located
Modifications in
Flowers
Complete flowers – have all four
organs (sepals, petals, stamens, and
pistils)
– M orning glory and tiger lily
Incomplete flowers – lacks one or
more of the four organs
– Squash and corn
Tiger Lily – a complete flower
Incomplete Flowers
Female Squash Flower
Male Squash Flower
Modifications in
Flowers
P erfect flowers- Have both stamens
and pistils (E x: Lily)
Imperfect flowers- E ither have a
functioning stamen or pistil, but not
both
E x : Cucumber, Squash
Pollination Mechanisms
Animal pollination
– hummingbirds & bees transfer pollen from
plant to plant
– Flowers are brightly colored or highly
scented
Wind pollination
– lightweight and are carried by wind
– Small flowers with little color or scent
Self pollination
– Able to pollinate flowers on same plant
– Have both pistel and stamen
Pollinators
PHOTOPERIODICITY
Plants flower based
on the number of
hours of darkness
they are exposed to
Short-day plants flower when days
are short (fall,
winter, spring)
Ex: Pansy,
Poinsettias
PHOTOPERIODICITY
Long-day plants flower when days
are long (summer)
Examples:
– Potatoes
– Clover
– Spinach
PHOTOPERIODICITY
Intermediate-day
plants- Grow when
darkness is about
equal to daylight.
E x : Sugar Cane
PHOTOPERIODICITY
Day-neutral plantsHours of darkness
does not effect
flowering, as long as
there is enough
daylight to perform
photosynthesis.
E x: Corn, tomatoes,
cotton, roses
Chapter 23.3
Flowering P lants
Flowering Plant
reproductive cycle
Sporophyte dominant
Ovary- produces 4 megaspores, but 3
disintegrate and only one remains.
Double fertilization – requires 2 sperm
to fertilize the egg and make a seed.
Seed – embryo (cotyledons),
endosperm (food for embryo), seed
coat (protect seed)
Flowering Plant
Reproduction
4 kinds of fruit
1. Simple Fleshy
fruits- contain
one or more
seeds.
Ex: Apples, Peach,
grape, tomato,
pumpkin
4 Kinds of fruit
2. Aggregate fruitMost berries.
Many female
parts fuse to
form one fruit.
Ex: Blackberries,
strawberries,
raspberries
4 Kinds of fruit
3. Multiple fruitFlowers fuse to
form one fruit.
Ex: Pineapples,
figs
4 Kinds of fruit
4.. Dry fruit- Fruits
that are dry.
Ex: Nuts, grains,
seed pods
Seed Dispersal
Water
– Coconuts
Wind
– Dandelions
Animals
– Fruits attract animals that will eat the
seeds so that the seeds can be carried
far away where it won’t have to compete
with its parent.
Seed Germination
Requires:
– Water (swells and breaks seed coat)
– Oxygen (cell respiration as seed grows)
– Optimal Temperature (each plant requires
a certain temperature to begin growth)
Seeds will lie dormant in their hard seed
coats waiting for optimal conditions.
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