1. Seed Bearing Plants

2. Alternation of Generations
All plant life cycles involve alternation of generations between the sporophyte and the gametophyte
In different types of plants the relationship changes
Mosses: the gametophye is the longest phase
Flowering plants: the sporophyte is the longest phase

3. Seeds Recall the definition of the seed
Tougher and more resistant to drying than spores
Most spores: single cell
Seeds: fully formed plant embryo and stored food; specialized for distribution
Evolution of the seed uncoupled reproduction from water

4. Cones and Flowers Contrast with the life cycle of the fern
Tiny gametophytes of the seed bearing plants do not have independent life of their own
Gametophytes life inside the sporophyte (in pine cones and flowers)
Two kinds of spores: pollen and eggs (these are not gametes in plants)

5. Reproduction in Conifers (gymnosperms)
Study the picture on page 582: the life cycle of a gymnosperm
Alternation of generations: gametophyte develops within the sporophyte
Two kinds of cones: male cones (produce pollen), female cones (produce eggs)
Typically fertilization and seed formation takes a year
Seed release is the next year

6. Reproduction in Angiosperms (flowering plants) 1
Angiosperms produce seeds encased in a protective tissue of the sporophyte called an ovary
The combination of seed and ovary is called a fruit
Specialized reproductive structure called the flower

7. Reproduction in Angiosperms (flowering plants) 2
Typical flowers produce both male and female gametophytes
Some have separate male and female flowers on the same plant (corn)
Some have separate male and female plants (willow)
Formed from 4 types of leaves (sepals, petals, stamens and carpels)
See diagram of flower on page 586

8. Reproduction in Angiosperms (flowering plants) 3
Flower parts
Sepals
Leaflike, green, protect the bud
Petals
Colorful, advertise the flower to pollinators
Stamens
Male leaves produce pollen (anther and filament make up the filament)
Carpels
Female leaves each has an ovary (stigma and style make up the pistil)

9. Reproduction in Angiosperms (flowering plants)
Follows the pattern of alternation of generations
Production of gametophyte, fertilization of eggs, development of seed takes place within the flower
See life cycle of an angiosperm on page 587

10. Reproduction in Angiosperms (flowering plants) 4
Key difference between gymnosperm life cycle and angiosperm is double fertilization
A sperm nucleus fuses with one of the 2n embryos to make a 3n cell; which divides to produce the endosperm (food for the embryo)
In angiosperms, endosperm is produced after the fertilization
In gymnosperms endosperm is produced before fertilization

11. Reproduction in Angiosperms (flowering plants) 5
Fertilization sets into action a number of events
Sepals and petals and stamens fall away,
Carpel thickens, nutrients directed to endosperm and walls of the ovary
This produces a fruit (an ovary containing seeds)
Review difference between monocots and dicots