1. GYMNOSPERMS
“Naked Seeds”

2. I can: Describe the characteristics of gymnosperms
Do Now: List two similarities and two differences between mosses and ferns:
HW: Check webpage for worksheet

4. Gymnosperms: General Characteristics
Vascular
Alternation of generations
Dominant sporophyte
Reduced, dependent gametophyte
Produce uncovered seeds
Pollen-

5. 4 main groups of Gymnosperms
Cycads
Gingko
Conifers
Gnetophytes

6. Strobilus of a “female” cycad
Cycads
Only 100 living species
Cones
Strobilus of a “female” cycad

7. Ginkgos One surviving species, Ginkgo biloba
Deciduous: lose their leaves during the winter
Seeds are completely exposed

8. Gnetophytes Cone clusters resemble flower clusters
Parts of life cycle more like angiosperms
Welwitschia –grows in Namib desert (So. Africa).
Live up to 2000 years

9. Conifers Widest known, largest number of living species
Woody trees or shrubs
Most are evergreen
Keep their leaves all year-round
Bear seeds on exposed cone scales
Most produce woody cones

10. I can: describe the characteristics of gymnosperms
Do Now: Give three characteristics of gymnosperms.

11. The Importance of Pollen and Seeds
Seed Reproduction 3
The Importance of Pollen and Seeds
Oak, maple, and other shade trees are seed plants.
All flowers are produced by seed plants. In fact, most of the plants on Earth are seed plants.
How do you think they became such a successful group? Reproduction that involves pollen and seeds is part of the answer.

12. Seed Reproduction 3
Pollen
In seed plants, some spores develop into small structures called pollen grains.
A pollen grain has a water-resistant covering and contains gametophyte parts that can produce the sperm.

13. Seed Reproduction 3
Pollen
The sperm of seed plants are carried as part of the pollen grain by gravity, wind, water currents, or animals.
The transfer of pollen grains to the female part of the plant is called pollination.

14. Seed Reproduction 3
Pollen
After the pollen grain reaches the female part of a plant, sperm and a pollen tube are produced.
The sperm moves through the pollen tube, then fertilization can occur.

15. Seed Reproduction 3
Seeds
A seed consists of an embryo, stored food, and a protective seed coat.
The embryo has structures that eventually will produce the plant’s stem, leaves, and roots.

16. Seed Reproduction 3
Seeds
The stored food provides energy that is needed when the plant embryo begins to grow into a plant.
A new plant can develop more rapidly from a seed than from a spore.

17. Gymnosperm Reproduction
Seed Reproduction 3
Gymnosperm Reproduction
Cones are the reproductive structures of gymnosperms.
Each gymnosperm species has a different cone.
The pine is a familiar gymnosperm.

18. Seed Reproduction 3
Cones
A pine tree is a sporophyte plant that produces male cones and female cones.
Male and female gametophyte structures are produced in the cones but you’d need a magnifying lens to see these structures clearly.

19. Seed Reproduction 3
Cones
A mature female cone consists of a spiral of woody scales on a short stem. At the base of each scale are two ovules.
The egg is produced in the ovule.
Pollen grains are produced in the smaller male cones.

20. Pine Cones
Woody scales of a “pine cone” are the parts where megaspores formed and developed into female gametophytes
Male cones, where microspores and pollen are produced, are not woody

21. Pine Cones

22. Seed Reproduction 3
Gymnosperm Seeds
Pollen is carried from male cones to female cones by the wind.
To be useful, the pollen has to be blown between the scales of a female cone.
If the pollen grain and the female cone are the same species, fertilization and the formation of a seed can take place.

23. Seed Reproduction 3
Gymnosperm Seeds
It can take a long time for seeds to be released from a female pine cone.
From the moment a pollen grain falls on the female cone until the seeds are released, can take two or three years.
Click image to view movie.

24. copyright cmassengale
The Life Cycle
Of a Gymnosperm
copyright cmassengale