Transcript Angiosperm Reproduction

Chapter 38
Angiosperm Reproduction
Angiosperms have 3 unique Features:
1.
2.
3.
Flowers
Fruits
Double Fertilization
SYMMETRY
OVARY LOCATION
FLORAL DISTRIBUTION
Bilateral symmetry
(orchid)
Lupine inflorescence
Superior
ovary
Radial symmetry
(daffodil)
Sepal
Fused petals
Semi-inferior
ovary
Inferior
ovary
Sunflower
inflorescence
REPRODUCTIVE VARIATIONS
Maize, a monoecious species
Dioecious Sagittaria latifolia (common
arrowhead)
Pollination: transfer pollen from anther to stigma
 Pollen tube grows down into ovary for 2 sperm to
travel to egg

Seed

Double
Fertilization
◦ The union of two
sperm cells with
different nuclei of
the embryo sac.
Makes the embryo
and the endosperm

Endosperm
◦ Food storing tissue
of the seed.
Some plants are self-pollinated
 Cross-pollinated plants:
◦ Self-incompatibility: plant rejects own pollen or
closely related plant
◦ Maximize genetic variation

Stigma
Stigma
Anther
with
pollen
Pin flower
Thrum flower
“Pin” and “thrum” flower types reduce self-fertilization
Seeds and Eggs

Seeds are plant
products which
encloses the embryo
with a hard coat and
food supplies.

Eggs are animal
products which enclose
an animal embryo with a
hard or leathery shell
and food supply.

Eggs are similar to seeds
because they protect
the embryo while
allowing gas exchange
From Ovule to Seed

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

After Double Fertilization, each ovule
develops into a seed.
These seeds carry enough food and
supplies until germination period.
Seeds sinks down because the Endosperm
is filled with the heavy supplies.
Cotyledons swell to show that the
Endosperm is filled with nourishment.
Endosperm
An example of liquid Endosperm are
the coconut milk.
 An example of solid Endosperm is
the coconut meat itself. Also the
white puff inside the popcorn is also
the endosperm.
 Seeds carry endosperms until they
are mature enough

The development of a plant embryo
Fruit





Egg cell  plant embryo
Ovules inside ovary  seeds
Ripe ovary  fruit
Fruit protects enclosed seed(s)
Aids in dispersal by water, wind, or animals
Types of Fruit
Seeds ********
Mature seed  dormancy (resting)
 Low metabolic rate
 Growth & development suspended
 Resumes growth when environmental
conditions suitable for germination
Seed
Structure
Germination

Seed take up water (imbibition)  trigger
metabolic changes to begin growth
1. Root develops
2. Shoot tip emerges above ground
 Stimulated by light
3. Foliage leaves expand & turn green 
photosynthesis

Very hazardous for plants due to vulnerability
 Predators, parasites, wind

The first organ to emerge from the germinating seed
is the radicle, the embryonic root.
◦ Next, the shoot tip must break through the soil surface.
◦ In garden beans and many other dicots, a hook forms in the
hypocotyl, and growth pushes it aboveground.
◦ Stimulated by light, the hypocotyl straightens, raising the
cotyledons and
epicotyl.
Seed
Germination
Seed to Seedling
http://students.usm.maine.edu/deidre.rice/_ILLUS_ILT_T630888A.GIF
Plant Reproduction
Sexual
Asexual
(Vegetative Reproduction)
Flower  Seeds
Runners, bulbs, grafts, cuttings
vegetative (grass), fragmentation,
test-tube cloning
Genetic diversity
Clones
More complex & hazardous for
seedlings
Simpler (no pollinator needed)
Advantage in unstable
environments
Suited for stable environments
Asexual reproduction in aspen trees
Test-tube cloning of carrots
Just a few parenchyma
cells from a carrot gave
rise to this callus, a mass
of undifferentiated cells.
The callus differentiates
into an entire plant, with
leaves, stems, and roots.
Humans Modify Crops
Artificial selection of plants for breeding
 Plant Biotechnology:
◦ Genetically modified organisms
 “Golden Rice”: engineered to produce betacarotene (Vit. A)
 Bt corn: transgenic – expresses Bt (bacteria)
gene  produces protein toxic to insects
◦ Biofuels – reduce CO2 emissions
 Biodiesel: vegetable oils
 Bioethanol: convert cellulose into ethanol

The seed of
knowledge has
sprouted..
♥
Plant yourself
in that chair…
1 more PPT to
go!!!!!!
♥