Angiosperm Reproduction
Chapter 19
Major Evolutionary Advances
Flowers - 140 mya
5,000mya
4,000mya
3,000mya
2,000mya
1,000mya
EarthForms
ProkaryoticCells
EukaryoticCells
MulticellularPlants
Vascular
tissue
Seeds
Flowers
Life - 3,800 myaProkaryotic cell/autotrophic
Eukaryotic cell - 1,400 myaMulticellar plants - 1,000 myaVascular tissue - 430 mya
Needed on land - why?Seeds - 350 mya
Place on the time scale, the following events:
1. Earth2. Prokaryotes3. Eukaryotes4. Multicellular life5. Vascular tissue6. Seeds7. Flowers
Flower variation
Complete• has all 4 whorls
Incomplete• lacks one or more
of whorls (sepals, petals, stamens or carpels)
Flower variationPerfect
• 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. Pollination2. Pollen grain growth to ovule3. Successful fertilization4. 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 ReproductionBisexual flowers
• Protandry - stamens mature before stigma
Hibiscus
MagnoliaEpilobium (fireweed)
Protandry
• Protogyny - stigma matures before stamens
• Heterostyly - physical separation between stigma and stamen
Sexual ReproductionBisexual 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:
ovule
• Define:• combining of sperm + egg AND sperm +
polar nuclei = double fertilization
Fertilization
megagametophyte(female gametophyte)
microgametophyte(male gametophyte)
ovule
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 plantsMale-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
What conclusions can be drawn?
• What conclusions can be drawn?• What is the role of gyno-dioecy in
plant reproduction and reproductive success in Callirhoe involucrata?
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.