1. Plant Diversity II
The Evolution of Seed Plants

2. SEEDS!
Seeds are plant embryos packaged with a food supply in a protective coat

3. Evolution of Plants

4. Five Reproductive Adaptations
Reduction of the gametophyte:
shift from haploid to diploid condition
female gametophyte and embryo depend on sporophyte
protection against drought
Protects the delicate antheridia and archegonia
Increasing reproductive success
Heterospory
Production of two types of spores
Megaspores – female gametophyte – eggs
Microspores – male gametophyte - sperm

5. Five Reproductive Adaptations
Ovules: production of eggs
Megasporangium, megaspore plus protective tissue = ovule
Increases protection of the egg and developing zygote
Increases reproductive fitness
Evolution of pollen
Male gametophyte = pollen grain
Contain two sperm nuclei
Waterproof coat for transfer by wind
Remember before – water was required for fertilization
THIS IS A KEY ADAPTATION

6. Five Reproductive Adaptations
Seeds
Advantages over spores
Multicellular
Layers of protective material
Supply of stored energy means seed can WAIT for good germination conditions
Stored energy supplements early growth of the embryo

7. Gymnosperms (bare naked)
Cone-bearing plants
Lack enclosed chambers (ovaries) for seeds
Ovules and seeds develop on specialized leaves called sporophylls
Ginkgo, cycads, and conifers
All are “evergreens”
Needle-shaped leaves
Vascular tissue refinement: tracheids~ water conducting and supportive element of xylem

8. Reproduction in Gymnosperms

9. Reproductive Cycle

10. Gymnosperm Life Cycle Sporophyte produce gametophytes inside of cones
Pollen cone (male)
produces microspore via meiosis
Ovulate cone (female)
produces megaspores via meiosis
Fertilization
pollen grains discharge sperm into egg

11. Angiosperms – Flowers and Fruits
Seed plants that produce the reproductive structures called flowers and fruits.
90% of all plant species
“Flowering plants” Anthophyta

12. The Flower defining structure of angiosperms
Reproductive structure: pollen transfer; specialized shoot with modified leaves
Sepals: enclose flower before it opens - protection
Petals: attract pollinators
Stamens: male, produce microspores in the anther that develops the pollen grain
Carpels: female, produce megaspores - stigma, style, ovary, ovules

13. Fruits Fruits are the mature ovaries of the plant
The wall of the ovary thickens to become the fruit.
The purpose of fruit is to disperse the seeds

14. Monocots and Eudicots Angiosperms are divided into two groups Monocots
~70,000 species
One cotyledon in the seed
Parallel leaf veins
Flowering parts in multiples of three

15. Monocots and Eudicots Angiosperms are divided into two groups Eudicots
~170,000 species
Two cotyledon in the seed
Net leaf veins
Flowing parts in multiples of fours or fives

16. Angiosperm life cycle