Plant Reproduction

1. Plant Reproduction

2. Asexual Reproduction • Asexual reproduction is natural “cloning.” Parts of the plant, such as leaves or stems, produce roots and become an independent plant.

3. Sexual Reproduction • Sexual reproduction requires fusion of male cells in the pollen grain with female cells in the ovule.

4. Plant Life Cycle

5. Alternation of Generations • Plants have a double life cycle with two distinct forms: • Sporophyte: diploid, produce haploid spores by meiosis. • Gametophyte: haploid, produce gametes by mitosis.

6. 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?

7. Moss Life Cycle

8. Fern Life Cycle

9. Moss life cycle: • http://www.youtube.com/watch?v=o1z0Vfo62Lg • Fern life cycle: • http://www.youtube.com/watch?v=Fhk-Y0duNjg

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. • Life Cycle: http://www.youtube.com/watch?v=WPfRV8NWkk4

13. Plant Reproduction Song • http://www.youtube.com/watch?v=35vPjdTNRU0

14. Flowers

15. Flower Parts

16. Male Reproductive Structure • The stamen consists of two parts: Anther and Filament • The anther is where meiosis occurs to produce haploid pollen • The filament is a stalk that supports the anther

17. Female Reproductive Structure • The pistil consists of the stigma, style and ovary • The sticky stigma receives the pollen from the anther • The pollen grows a tube down through the style • Meiosis occurs in the ovary to produce haploid ovules

18. Pollination • Wind, insects or other animals transfer pollen from the anther of one flower to the stigma of another • Flowers vary depending on pollination mechanism

19. Fertilization • After pollen lands on the stigma, a pollen tube grows down through the style to ovary • Generative cell creates the two sperm nuclei • Double fertilization occurs: • one sperm fertilizes the egg • one sperm the two polar nuclei together

20. Angiosperm Life Cycle

21. Gametogenesis: Male

22. Gametogenesis: Female

23. Double Fertilization

24. Result of Double Fertilization • The sperm nucleus and egg nucleus join to form a 2n (diploid) embryo • The other sperm nucleus and the two polar nuclei join to form a 3n (triploid) endosperm. The endosperm is the food supply for the embryo. • First link

25. Flower to Fruit

26. Seed and Fruit Development • After fertilization, the petals and sepals fall off flower • Ovary “ripens” into a fruit • The ovule develops into a seed

27. Seed Dispersal Mechanisms Wind Dispersal - Flight mechanisms, like parachutes, wings, etc. Ex. Dandelion, maples, birch Animal Dispersal - Fleshy fruits which animals eat, drop undigested seeds in feces or burrs which stick to animals’ coats

28. Gravity Dispersal - Heavy nuts fall to ground and roll ex. acorns Water Dispersal - Plants near water create floating fruits ex. coconuts