This document summarizes key trends in plant evolution such as the reduction of the gametophyte generation and specialization of the sporophyte generation. It also describes the development of vascular tissue which improved water and nutrient transport within plants. Additionally, it reviews plant classification including bryophytes, seedless vascular plants like ferns and horsetails, gymnosperms, and flowering plants. Seedless vascular plants were dominant during the late Devonian through early Permian time periods but today are more marginal in their success.

1. Continuing Trends in PlantContinuing Trends in Plant
EvolutionEvolution
• Reduction of water-dependent gametophyte
• Vascular tissue – improved water/food
transport
• More efficient roots, stems, leaves
* Tissues
* Stomates
Green: all these are in sporophyte

2. Reduction of gametophyte
Specialization in sporophyte

3. Vascular tissueVascular tissue
• In sporophyte
• Interconnects all plant
organs
• Xylem - water
• Phloem - sugar

4. Complex leavesComplex leaves
• Tissues
• Stomates

5. Plant classification reviewPlant classification review
• Bryophytes – no seeds, no roots, no vascular
* Mosses, liverworts, hornworts
• Seedless, vascular plants – no seeds
* Ferns, horsetails, club mosses, whisk ferns
• Gymnosperms - seeds & cones
* Conifers, cycads, ginkgo, gnetophytes
• Flowering plants – seeds, flowers & fruits
* Primitive, Monocots, Dicots

6. Seedless Vascular PlantsSeedless Vascular Plants
• Ferns, horsetails, club mosses, whisk ferns
• Sporophyte dominant
• Gametophyte small but still tied to water
• Dominant plants from late Devonian
through early Permian
* Equatorial coal forests
• Today somewhat marginal, but successful
• Heterospory in some (next time)

8. Fern Life CycleFern Life Cycle
Gametophyte
Fertilizatio
n
Sporophyte
M
eiosis

9. Fern gametophytes …
… with young sporophytes
Mature fern sporophyte …
… with clusters of sporangia

10. Whisk Fern, Psilotum

11. Club moss, Lycopodium

12. Horsetail, Equisetum

13. Carboniferous (-300 my) coal forest model