1. Ch – 22.5
Flowering plant reproduction, germination, dispersal, and hormone response

2. Flower reproduction
Sepals: modified leaves that protect the developing flower (outer most layer)
Petals: layer just inside sepals. Brightly colored to attract pollinators
Stamen: male reproductive structure made up of anthers and filament
Carpel: female reproductive structure made up of stigma, style, and ovary

3. Pollinators:
Flower can be pollinated by wind or animals

4. Pollination and fertilization
Pollination: pollen grain sticks to the stigma
Double fertilization: after pollination, pollen grain grows a pollen tube to the ovule. Two sperm cells travel down the pollen tube.
One sperm fertilizes the egg one sperm: combines with the polar nuclei in the embryo sac. This cell is now triploid ( 3n)
Endosperm: 3n nucleus will become the endosperm (food supply for embryo)
Double fertilization: process of one sperm fertilizing an egg and the other forming a triploid cell

6. Fruit After fertilization: ovule become the seed
While seed develops, ovary grows into a fruit

7. Seed dispersal and germination
Animals, wind, and water can spread seeds
Seeds can stay dormant for long periods of time and then grow when conditions are favorable
2000 year old date palm seed found, planted, and grown
Germination: embryo begins to grow into seedling

9. Asexual reproduction
Regeneration: process by which some plants grow a new individual from a fragment of stem, leaf, or root
Vegetative reproduction: asexual reproduction in which a stem, leaf, or root attached to a parent plant grows a new individual

10. Types of asexual reproduction
Plant structures that are specifically adapted for vegetative reproduction
Stolons: horizontal stems (runners) that take root and grow into a new plant
Rhizomes: underground horizontal runners that grow into a new plant
Tubers: an underground stem modified for storage. They produce buds that can sprout a new plant….. potatoes
Bulbs: underground stems which are surrounded by modified leaves adapted for storage and covered with a protective skin. Under favorable conditions, will grow into a new plant

12. Plant hormones
Hormones: chemical messengers produced in one area of an organism that stimulates or suppresses activity of cells in another area.

13. Plant hormones
Gibberellins: hormone that produces dramatic increase in size
involved in ending seed dormancy, germination,
rapid growth of young seedlings, and large size of fruits
- Used by growers to help plants produce longer stems and bigger fruit

14. Plant hormones
Ethylene: plant hormone that causes ripening and is naturally occurring in fruits
growers use ethylene to their advantage: filter it out to cause
a delay in ripening or gas to artificially ripen

15. Plant hormones
Cytokinins: plant hormone that stimulates cytokinesis (division of the
cytoplasm). Final stage of cell division. Produced in growing
roots, developing seeds, and fruit. Associated with lateral growth.
- Used to slow aging process of some plant organs… floral leaves

16. Plant hormones
Auxins: plant hormone involved in the lengthening of cells produced
in the apical meristem (growing tip). Stimulates the growth of
primary stems.
- used by growers to control growth by removing growing tips from plants
High concentrations prevents plant growth (especially in roots)
Used in many herbicides to kill unwanted plants
Build up of auxins on the shaded side of a stem causes it to bend toward the light… phototropism
Tropism: movement of a plant in response to an environmental stimulus