Plant Diversity II: The Evolution of Seed Plants

1
Plant Diversity IIThe Evolution of Seed Plants

• Overview of Reproductive Adaptations
• Gymnosperms
• Angiosperms

2
Reproductive Adaptations of Seed Plants

• Reduced gametophyte-retained within the
  sporophyte
• Origin of the seed-protected embryo and key
  dispersal structure
• Pollen-no longer a need for external water for
  fertilization

3
(No Transcript)
4
Gymnosperms

• Evolved during Mesozoic era
• naked seed
• Conifers are largest division
• Characterized by
• 1. Thick cuticle
• 2. Recessed stomata
• 3. Long, thin leaves (needles)

5
Figure 30.9 The life cycle of a pine (Layer 1)
6
Figure 30.9 The life cycle of a pine (Layer 2)
7
(No Transcript)
8
Role of Cones

• Two types
• 1. Pollinate cone-male, pollen producting,
• contains microgametophyte, seasonal
• 2. Ovulate cone-female, contains
• megagametophyte

9
(No Transcript)
10
Angiosperms

• Flowering plants
• Monocots and dicots
• Many dependent upon insects for pollen dispersal
• Flower-key reproductive adaptation, many
  variations
• Importance of fruit

11
Flower

• Evolved from modified leaves
• Four evolutionary trends
• 1. Number of parts have become reduced
• 2. Parts fused
• 3. Radial?bilateral symmetry
• 4. Position of ovary changed

12
(No Transcript)
13
Pollen Grains
14
Seed and Fruit

• The seed contains
• Embryo
• Cotyledon(s)
• Seed coat
• Function
• Dispersal
• Protection
• Dormancy?

• Functions of the fruit
• Protection?
• Dispersal?

15
(No Transcript)
16
(No Transcript)
17
Videos and Websites

• http//www.youtube.com/watch?v35vPjdTNRU0