Angiosperm Reproduction
Chapter 19
Major Evolutionary Advances
Life - 3,800 mya
Prokaryotic cell/autotrophic
Eukaryotic cell - 1,400 mya
Multicellar plants - 1,000 mya
Vascular tissue - 430 mya
Needed on land - why?
Seeds - 350 mya
Place on the time scale, the
following events:
1. Earth
2. Prokaryotes
3. Eukaryotes
4. Multicellular life
5. Vascular tissue
6. Seeds
7. Flowers
Flowers - 140 mya
Earth
Forms
5,000
mya
Prokaryotic
Cells
4,000
mya
Eukaryotic
Cells
3,000
mya
2,000
mya
Multicellular
Plants
1,000
mya
Vascular
tissue
Seeds
Flowers
Flower variation
Complete
• has all 4 whorls
Incomplete
• lacks one or more
of whorls (sepals,
petals, stamens or
carpels)
Flower variation
Perfect
• both androecium and
gynoecium
Imperfect
• carpellate or staminate
flower only
• if both carpellate and
staminate flowers are
on same plant called
monoecious
• if on different plants
called dioecious
Fertilization
• Pollination: transfer of
pollen grains from anther
to pistil
• Pollen grain onto stigma
• Germination - tube cell
produces pollen tube,
generative cell divides to
form 2 sperm cells
• Double Fertilization:
•
2 sperm enter embryo
sac:
•
•
1 sperm fertilizes egg to form zygote
other sperm fertilizes polar nuclei to
form endosperm
Sexual Reproduction
Four events must occur for successful
reproduction in angiosperms:
1.
2.
3.
4.
Pollination
Pollen grain growth to ovule
Successful fertilization
Successful seed development
Sexual Reproduction
• Inbreeding
• Result of self-pollination & self-fertilization
• Results in inbreeding depression
• Outcrossing
• Result of cross-pollination & cross-fertilization
• Results in hybrid vigor
• What process is “best”? Why?
• How do plants promote this?
Sexual Reproduction
• Unisexual flowers
• Monoecious plants
• Dioecious plants
Sexual Reproduction
Bisexual flowers
• Protandry - stamens mature before
stigma
• Protogyny - stigma matures before
stamens
• Heterostyly - physical separation
between stigma and stamen
Hibiscus
Protandry
Epilobium (fireweed)
Magnolia
Sexual Reproduction
Bisexual flowers
Self-incompatibility
• Pollen grain-stigma
surface: no
germination
• Pollen tube growth:
tube “dies”
• Fertilization:
inviable zygotes
Amarylis
Pollination
• Define:
• transfer of pollen to stigma
• How is self-fertilization prevented (or
reduced) through pollination
mechanisms?
•
•
•
•
•
unisexual flowers (monoecious plants)
unisexual flowers (dioecious plants)
protandry
protogyny
heterostyly
Fertilization:
• Define:
• combining of sperm + egg AND sperm +
polar nuclei = double fertilization
ovule
Fertilization
megagametophyte
(female gametophyte)
ovule
microgametophyte
(male gametophyte)
Fertilization
Fertilization
• What occurs after double
fertilization?
• embryo development
• next generation
• endosperm development
• nourishment for embryo
• What structure is formed?
• seed
• embryo
• endosperm
• seed coat
• Where is the seed housed?
• inside ovary
• matures into a fruit
• ovary wall = pericarp
Seed germination & growth
How might reproductive success be
measured in an angiosperm?
Funk, Lisa. 1997. A comparison of reproduction in
self and outcrossed purple poppy mallow flowers
(Callirhoe involucrata). Results presented at the
1997 Nebraska Academy of Sciences Annual
Meeting.
Gyno-dioecious
species
Hermaphroditc
flowers on some plants
Male-sterile flowers
on other plants
Funk, Lisa. 1997. A comparison of reproduction in
self and outcrossed purple poppy mallow flowers
(Callirhoe involucrata). Results presented at the
1997 Nebraska Academy of Sciences Annual
Meeting.
4 Treatments
•
•
•
•
Selfed
Outcrossed
Pollinator excluded
Control
Fruit set measured
Pollination study in purple poppy
mallow (Callirhoe involucrata). Lisa
Funk, 1997
What conclusions can be drawn?
90
80
70
60
% fruit 50
formed
40
30
20
10
0
self
outcross
pollinator
excluded
control
Funk, Lisa. 1997. A comparison of reproduction in self and
outcrossed purple poppy mallow flowers (Callirhoe involucrata).
Results presented at the 1997 Nebraska Academy of Sciences
Annual Meeting.
• What conclusions can be drawn?
• What is the role of gyno-dioecy in plant
reproduction and reproductive success
in Callirhoe involucrata?