Download Plant Reproduction2

Sexual Reproduction of Flowering
Plants
Topics: 2022D, 2022E, 2022F, 2022G
Amanda Trutsch
Sexual Reproduction includes:
- Pollination
- Fertilization
- Seed production
*NOTE: Pollination and fertilization are separate
processes!
Parts of a flower:
http://www.ualr.edu/~botany/flower_parts.jpg
Pollination is:
the process of moving the pollen grain from the anther of
a stamen (male organ) to the stigma of a carpel (female
organs). Pollen contains sperm cells.
Self-pollination is:
the transfer of pollen from the anther of a flower to the
stigma of the same flower, or to different flowers on the
same plant.
Cross-pollination is:
the transfer of pollen from the anther of a flower to the
stigma of a flower on a different plant.
Self-pollination:
- More effective
- Almost guarantees pollination
- Isn’t dependent on outside variables for pollination
Cross-pollination:
- Increases genetic variability
Methods of Pollen Distribution:
- Wind: pollen grains are carried by wind from one flower to
another
- Animals:
Birds (hummingbirds)
Insects (moths, butterflies, bees, flies)
Mammals (bats)
Flowers of wind pollinated plants are:
- Small
- Greenish or brown
- No fragrance
- Small or no petals
- No nectar
http://www.epa.gov/owow/wetlands/types/images/cattail.jpg
Examples include:
Grasses, wheat or cattails
Flowers that are pollinated by hummingbirds and
butterflies are:
- Tube shaped
- Fragrant for butterflies, no fragrance for
hummingbirds
- Brightly colored, usually red attracts hummingbirds
- Produce nectar which is an attractive “snack”
http://www.indirectsunlight.com/images/scotland/2003-09-10/2003-09-11--Red%20flower.jpg
http://ppng.home.comcast.net/abc/Butterfly_Bush_Lavendar.jpg
Flowers that are pollinated by flies:
- Brown or dark colored
- Have a foul odor
http://digital-picture-gallery.com/Orchids-LR-PO-SG/thm_Brown%20Spotted%20Orchid.jpg
Flowers that are pollinated by bees are:
- Fragrant (nectar as a “reward”)
- Brightly colored with nectar guides visibly only
with UV light that bees can see, which directs
bees to the center of the flower
- Sweet fragrance
- Produce nectar
http://www.mooseyscountrygarden.com/flowering-annuals/pansy-flower.jpg
Flowers that are pollinated by bats or moths:
- Tube shaped
- Fragrant
- White or yellow which can be seen easily at night
- Sometimes only open at night
http://fcbs.org/images/Tillandsia/t_streptocarpa_white_flowers_hp.jpg
Fertilization: process of sperm reaching the egg
- Cells of many plant flowers are diploid (two sets of
chromosomes). Represented by 2n
- Some of these cells undergo a process of cell division
called miosis. This process causes the chromosomes
number to be halved and the result are the “daughter cells”.
- The daughter cells are haploid (one set of chromosomes).
Represented by 1n
- The daughter cells undergo another process of cell
division called mitosis, which produce more haploid egg or
sperm cells.
- When these cells come together (fertilization) they form
the zygote, which is then diploid.
zygote.swarthmore.edu/ plantfig10.gif
Process of Fertilization
- After the pollen grain lands on the stigma, it develops a
pollen tube which travels down the style.
- The pollen grain releases a sperm cell, in some cases 2
sperm cells.
- The sperm travel down the pollen tube and reach the
ovary then enter the ovule.
- If there are 2 sperm cells, one fertilizes the egg while
the other fuses with another cell and produce the
endosperm. This is called double fertilization.
http://www.saburchill.com/images04/0107.jpg
Development of Seed
- The diploid zygote forms the embryo. These cells
will later divide and form parts of the seed.
- Cells in the outer layer of the ovule harden and become
the seed coat.
- The endosperm grows and becomes the food source for
the growing seed.
3 Essential Parts of a Seed:
- Embryo
- Embryonic root (radicle)
- Shoot (plumule)
- Food Reserve (endosperm in a monocot, cotyledon in a
dicot)
- Seed coat
www.huntersponyfarm.com/ garden/seeds_di_mono.gif
www.huntersponyfarm.com/ garden/seeds_di_mono.gif