1. Plant Diversity II – The Evolution of Seed Plants

2. Seeds and Pollen Grains are Key Adaptations for Life on Land
Seeds are embryos packaged with a food supply in a protective coat

3. Adaptations that led to success of seed plants
Reduced Gametophyte:
Gametes mostly microscopic
Dependent on the sporophyte for food and protection
Protects anteridia and achegonia, increasing reproductive success

4. Heterospory: Production of two types of spores
Megaspores produce female gametophytes which produce the egg.
Microspores produce male gametophytes which contain sperm nuclei.

5. Ovules and Production of Eggs
Megasporangium, megaspore, and the protective tissue around them make up the ovule.
Ovule increases protection of the egg and the developing zygote.
Increases reproductive fitness.

6. Pollen and the Production of Sperm
A Pollen grain is a male gametophyte.
It contains two sperm nuclei.
Has a waterproof coating, allowing for transfer by the wind.
Water no longer required for sperm transfer.

7. Seeds Have many advantages over spores. Multicellular and many layered
Can provide more protection for devloping embryo
Have a supply of stored energy which allows the seed to wait for good germination conditions.
Stored energy is used for early growth of embryo.

8. Germinating Seeds

9. Seed Plants are Divided into Gymnosperms and Angiosperms

10. Gymnosperms have “naked” seeds typically on cones
“Naked Seeds” means seeds are not enclosed in ovaries.
Seeds are exposed on modified leaves that form cones
Angiosperms (flowering plants) have seeds enclosed in fruits.
Gymnosperms do not have fruits.

11. Four Phyla of Gymnosperms
Cycadophyta
Ginkophyta
Gnetophyta

12. Coniferophyta: Largest group of gymnosperms Most are evergreen
Make up large forests in Northern hemisphere at high latitudes and altitude.
Includes the pines, firs, spruces, and redwoods.

15. Reproductive Adaptations of Angiosperms Include Flowers and Fruits.
Flowering plants are in the phyla Anthophyta
90% of all plant species are angiosperms.

16. Major Reproductive Adaptation of Angiosperms is the Flower
Flower consists of four floral organs:
Sepals - protect the flower before emergence
Petals - attract pollinators
Stamens - male reproductive structure
produces microspores in the anthers that develop into pollen grains.
Carpels - the female reproductive structure produces megaspores and their products: female gametophytes with eggs.

18. Fruits Fruits are mature ovaries.
Seeds develop from fertilized ovules.
The wall of the ovary thickens to become the fruit.
Fruits help disperse the seeds of angiosperms.

22. Angiosperms are divided into Moncots and Eudicots (dicots)
Monocots have:
One cotyledon in the seed
Parallel leaf veination
Flowering parts in multiples of threes
Vascular bundles are scattered through out the stem.

23. Dicots have: Two cotyledons in the seed Net leaf veination
Flowering parts in multiples of fours or fives.
Vascular bundles are found around edge of stem.