BIOL 112 Lecture 21

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Trends in Plant Evolution

Gametophyte gets smaller and more protected; Sporophyte becomes more dominant form.

Seedless Vascular Plants

Derived characteristics and advantages

1. Vascular structures (xylem and phloem) allow water, minerals, and food to be transported through plant: Plant can become larger and compete better for resources (esp. light)
2. Sporophylls: leaves that have sporangia on underside
3. Bisexual Gametophyte (archegonia and antheridia on same structure)

Formed forests of carboniferous period: larger and more diverse than current seedless vascular plants.

forests → fossil fuels of today

Seeded Plants

2 types:

• Gymnosperms (earliest seeded plants)
• Angiosperms (current dominant plant)

1. Seed: less dependence on H₂O for reproduction and increased dispersal efficiency
2. Pollen: Also decreased dependence on water for fertilization
3. Flowers: (angiosperms only): Increased fertilization and dispersal efficiency via animal vectors