1. Creating the next generation
Plant Reproduction
Creating the next generation

2. Asexual Reproduction
Asexual reproduction is natural “cloning.” Parts of the plant, such as leaves or stems, produce roots and become an independent plant.
List some benefits and some drawbacks to asexual reproduction.
Fast, no mate required.
Beneficial for plants that must compete for scarce resources.
However, all individuals are genetically identical.

3. Sexual Reproduction
Sexual reproduction requires fusion of male cells in the pollen grain with female cells in the ovule.
List some advantages and drawbacks to sexual reproduction.
Fusion of egg and sperm cells.
May be limited to a certain season.
Slower than asexual reproduction.
Allows genetic mixing, increasing variability in a population.

4. Terms to know:
Haploid: having a single set of chromosomes in each cell.
Diploid: having two sets of chromosomes in each cell.
Mitosis: cell division, which produces two genetically identical cells.
Meiosis: reduction division, which produces four haploid reproductive cells.

5. Plant Life Cycle

6. Alternation of Generations
Plants have a double life cycle with two distinct forms:
Sporophyte: diploid, produce haploid spores by meiosis (reduction division).
Gametophyte: haploid, produce gametes by mitosis (simple cell division).

7. Non-flowering plants
Mosses, ferns, and related plants have motile, swimming sperm.
What kind of environmental conditions would be required for reproduction in these plants?
What kinds of limits does external reproduction impose on these plants?
Reproduction in these plants requires wet conditions, and requires having male and female parts close together.
Living conditions, plant size, and genetic mixing is limited.

8. Moss Life Cycle

9. Fern Life Cycle

10. Conifers
Conifers (also non-flowering plants) have reduced gametophytes.
Male gametophyte is contained in a dry pollen grain.
Female gametophyte is a few cells inside of the structures that become the seed.

11. Conifer life cycle

12. Conifer pollination Conifers are wind-pollinated plants.
Chance allows some pollen to land on the scales of female cones.
Pollen germinates, grows a pollen tube into the egg to allow sperm to fertilize the egg.
What are some advantages and disadvantages to wind pollination?

13. Animals vs. Plants Plant Reproduction Animal Reproduction Life cycle
Alternation of generations
No alternation of generations
Gametes
Haploid gametes
Spores
Haploid spores
No spores
Gametes made by
Haploid gametophyte, by mitosis
Diploid organism, by meiosis
Spores made by
Diploid sporophyte, by meiosis

14. Flowers

15. Pollen go-betweens
Showy flowers are the result of selection for more efficient pollination strategies.
Flower parts are modified leaves. Those that were brightly colored attracted insects in search of pollen.
Why would insects search for pollen? What other rewards do flowers offer?
What are advantages and disadvantages to relying on insects as pollinators?
Pollen itself is a protein-rich food for insects. Some plants offer other rewards, such as nectar.

16. Flower Parts

17. Incomplete flowers
Flowers are complete if they have all parts, and perfect if they have both male and female parts.
Grass flowers: incomplete, usually imperfect (separate male and female flowers)
A tulip is complete (though the sepals are the same color as the petals) and perfect.

18. Imperfect flowers

19. Angiosperm Life Cycle

20. Gametogenesis: Male

21. Gametogenesis: Female

22. Double Fertilization

23. Fruits

24. From ovary to fruit The ovary of the flower contains the ovules.
As fertilized ovules develop into seeds, the ovary wall develops into the fruit.
In science, the term “fruit” refers to a mature ovary that contains seeds.

25. Flower to Fruit

26. Types of dry fruits Capsule (Poppy) Legume (Bean pod) Achene
(Sunflower)
Follicle
(Columbine)
Silique
(Money Plant)
Nut
(Hazelnut)

27. Types of fleshy fruits Drupe (Peach) Pome (Apple) Pepo (Cucumber)
Berry
(Tomato)
Aggregate
(Strawberry)
Multiple
(Pineapple)

28. Seeds

29. Ovule to seed

30. Seed Anatomy

31. Seed anatomy

32. Seed dormancy
Seeds can remain dormant in the soil for long periods of time. Dormancy helps ensure that seeds only germinate when conditions are right.
When we weed or cultivate a bare patch of soil, the weeds that sprout up immediately usually come from the “seed bank” already in the soil.

33. Breaking dormancy
Seeds require moisture and the right temperature to germinate.
In addition, some seeds germinate only after certain environmental signals:
Drying
Temperature (period of cold or heat)
Disruption of the seed coat

34. Seed Germination