Sexual Reproduction in Plants C10L3P2

Sexual Reproduction
in Plants
C10L3P2
Genesis 1:11-13
11 Then God said, "Let the earth bring forth
grass, the herb that yields seed, and the fruit tree
that yields fruit according to its kind, whose seed
is in itself, on the earth"; and it was so.
12 And the earth brought forth grass, the herb
that yields seed according to its kind, and the
tree that yields fruit, whose seed is in itself
according to its kind. And God saw that it was
good.
13 So the evening and the morning were the
third day.
Sexual reproduction
occurs when a
plant’s sperm
combines with a
plant’s ovum. The
resulting zygote can
grow into a plant that
is a genetic
combination of its
parents.
How do seed plants reproduce?
• Unlike seedless plants, the haploid generation of
a seed plant is within diploid tissue.
• Separate diploid male and diploid female
reproductive structures produce haploid sperm
and haploid eggs that join during fertilization.
In plants gametes are
produced in flowers,
cones, or other special
structures.
How do seed plants reproduce?
• Flowerless seed plants are known as
gymnosperms.
• The most common gymnosperms are
conifers, such as pines, firs, cypresses,
redwoods, and yews.
• Cones are the male and female reproductive
structures of conifers.
Two Types of Cones
Staminate and Ovulate
Staminate Cones
The pollen-producing
cones
Small, green, and
inconspicuous near
the tips of the
branches
Shed after the pollen
season is over
Ovulate Cones
The seed-producing cones
Larger than staminate cones
Size range: 1-2 inches
Woody structures
consisting of layers of
cone scales
Seeds develop between the
cone scales
Seeds are generally winged
How do seed plants reproduce?
• Flowering seed plants are called
angiosperms.
• Reproduction of an angiosperm begins in a
flower, most of
which have male
and female
reproductive
structures.
Flowers have one primary
function for the plant: to produce
seeds for reproduction.
A flower’s
color, shape,
and smell is
designed by
God to help
carry out the
flower’s
reproductive
processes.
Flowers
A typical
flower
consists of
4 different
types of
appendages
[sepals,
petals,
stamens,
carpels
(pistils)].
Arrangement of flower parts
• sepals – outermost
• petals – inside sepals
• stamens – inside petals
• carpels – in the center
There may be few
or many of each of
the four types, but
each type usually is
positioned on the
flower base in the
same relative
location.
sepal
the leaflike
outermost structure
of a flower; usually
green (some
exceptions like the
tulip – the tulip’s
sepals are the same
color and size as its
petals
sepal
(collectively called the calyx)
protects the other floral parts as they
develop in the bud
petal
any of the brightly
colored leaflike
structures (often
the largest and
most colorful
parts)
petal
(collectively called
the corolla)
they attract
insects and
animals with their
showy colors and
sweet nectar
the male reproductive
part of a flower
the organ which
produces pollen
(contains sperm)
stamen
Two parts of the stamen
• Filament
• Anther
filament
slender,
elongated
stalk
bears the
anther
anther
the enlarged
structure at the
tip of the
stamen (knobby
sac)
produces the
pollen
pollen
each kind of
pollen has a
definite shape
and surface
texture; many
are covered
with spikes or
knobs
Carpels (pistil)
elongated, vaseshaped female
reproductive
part of a flower
the central
structure in a
flower
Parts of the Carpel
• Stigma
• Style
• Ovary
stigma
the tip of the
pistil that
receives pollen
(often sticky)
style
the stalklike
structure of
the pistil
ovary
the swollen
base of the
pistil that
contains the
future seeds
ovules
the future
seeds
(contain ova)
How do seed plants reproduce?
• A pollen grain forms in a male reproductive
structure of a seed plant.
• Pollen grains produce sperm cells which can
be carried to female reproductive structures
by wind, animals, gravity, or water currents.
• The female reproductive structure of a seed
plant where the haploid ovum develops is
called the ovule.
pollination
the transfer
of pollen
from an
anther to the
stigma
types of pollination
self-pollination: occurs in the same
flower or with another flower of the
same plant
cross-pollination: from the anther of
one plant to the stigma of a flower
on another plant
Self-pollination
Cross-pollination
How do seed plants reproduce?
• Following pollination, sperm enter the ovule
and fertilization occurs.
• A zygote forms and develops into an
embryo, an immature diploid plant.
How do seed plants reproduce?
An embryo, its food supply, and a protective
covering make up a seed.
after pollination
the fertilized ovum is a zygote that
grows into a tiny embryo plant
the ovule develops into a seed (The
seed contains the embryo, some
stored food, and a protective coat)
the ovary develops into a fruit