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Plant Diversity II: The Evolution of Seed Plants. Overview of Reproductive Adaptations Gymnosperms Angiosperms. Reproductive Adaptations of Seed Plants. Reduced gametophyte-retained within the sporophyte Origin of the seed-protected embryo and key dispersal structure
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Plant Diversity II:The Evolution of Seed Plants Overview of Reproductive Adaptations Gymnosperms Angiosperms
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
Gymnosperms • Evolved during Mesozoic era • “naked seed” • Conifers are largest division • Characterized by: 1. Thick cuticle 2. Recessed stomata 3. Long, thin leaves (needles)
Role of “Cones” • Two types: 1. Pollinate cone-male, pollen producting, contains microgametophyte, seasonal 2. Ovulate cone-female, contains megagametophyte
Angiosperms • Flowering plants • Monocots and dicots • Many dependent upon insects for pollen dispersal • Flower-key reproductive adaptation, many variations • Importance of fruit
Flower • Evolved from modified leaves • Four evolutionary trends 1. Number of parts have become reduced 2. Parts fused 3. Radialbilateral symmetry 4. Position of ovary changed
The seed contains: Embryo Cotyledon(s) Seed coat Function: Dispersal Protection Dormancy? Functions of the fruit: Protection? Dispersal? Seed and Fruit
Videos and Websites • http://www.youtube.com/watch?v=35vPjdTNRU0