1. Reproduction of Seed Plants
Pg. 609

2. Alternation of Generation
All plants have a life cycle in which a diploid sporophyte generation alternates with a haploid gametophyte generation.
Gametophyte plants produce male and female gametes – sperm and eggs.
When the gametes join, they form a zygote that begins the next sporophyte generation.
Seed-bearing plants are diploid.
The gametophytes of seed plants are actually hidden deep within tissues of the sporophyte plant.
In gymnosperms they are found in cones.
In angiosperms they are found inside flowers.

3. Life Cycle of Gymnosperms
Reproduction in Gymnosperms takes place in cones which are produced in the mature sporophyte plant.
Pollen cones are male cones.
Seed cones are female cones and contain ovules.

4. Life Cycle Continued…
1. The mature sporophyte produces male and female cones.
2. Male cones produce pollen and female cones produce ovules.
3. If an egg is fertilized by the sperm, it becomes a zygote that is nourished by the female cone.
4. In time, the zygote develops into a new sporophyte plant.

5. Gymnosperm Life Cycle

6. Structure of Flowers
Flowers are reproductive organs that are composed of four kinds of specialized leaves:
1. Sepals – the outermost circle of floral parts. Enclose the bud before it opens, and protect the flower while it is developing.
2. Petals – brightly colored; attract pollinators to the flower.

7. Structures cont.
3. Stamen – male parts that consist of an anther and filament.
Filament – long thin stalk that supports the anther.
Anther – Produces pollen grains.
4. Carpels –produce female gametophytes.
Ovary – contains one or more ovules.
Style – stalk that holds the stigma.
Stigma – where pollen grain stick.

8. Life Cycle of Angiosperms
Reproduction in angiosperms takes place within the flower.
Following pollination and fertilization, the seeds develop inside protective structures.
1. The cycle begins when the mature sporophyte produces flowers.
Each flower contains anthers and an ovary.
2. Gametophytes develop to form pollen and ovules.
3. Pollen is transferred from pollen to stigma by a process called pollination.
4. After pollination occurs a pollen tube forms that grows into the style.
An endosperm forms – food rich tissue that nourishes the seedling as it grows.
5. Because two fertilizations take place, this is known as Double Fertilization.

9. Angiosperm Life Cycle

11. Review Question…
1. What are the reproductive structures of gymnosperms?
2. Describe the flower and how it is involved in reproduction.
3. Are angiosperms typically wind pollinated or animal pollinated? How does this process take place?
4. What is an endosperm? Where does it form in a flowering plant?
5. Many flowers have bright patterns of coloration that directly surround the reproductive structures. How might this type of coloration be advantageous to the plant?