1. Continuing Trends in Plant Evolution Extreme reduction of water-dependent gametophyte Vascular tissue – improved more Even more efficient roots, stems, leaves Seeds – protection/dispersal of young Wood – support Green: all these are in sporophyte

2. Seeds Produced by sporophyte Immature seed = ovule (female gametophyte +) Mature seed functions: *Protection *Embryonic sporophyte *Food source Also: Pollen grains = reduced male gametophytes

3. From Ovule to Seed Conifer ovulate scaleConifer pollen grain Conifer gametophytes

4. Seeds some more Spores not dispersed Reduced gametophytes *Female stays on sporophyte *Male (pollen grain) dispersed Embryo stays on parent sporophyte Delayed sporophyte development *Dormancy *Seed dispersal *Germination Conifer seed

5. Wood Secondary growth in circumference Increased support Reach great heights

6. First seed plants Pregymnosperms Early Permean Pangea – dry, continental climates

7. Gymnosperms Seeds naked *Often born on scales (modified leaves) of cones *No fruit Conifers, cycads, ginkgo, gnetophytes Some still produce motile sperm Except for conifers, mostly tropical & subtropical First gymnosperms developed in late Permean

8. Phylum Coniferophyta Conifers Dominate our biomes Well adapted to cold & dry summers Life cycle typical of gymnosperms *Seeds naked – no fruit *Two kinds of cones Male produce spores that grow into pollen grains Female produce spores that grow into ovules

9. Young & old female cones Male cones Pinus ponderosa

10. Sporophyte Gametophytes Meiosis ♀ ♂ Fertilization Pollination Seed dispersal & germination Megaspores inside megasporangium one functional Microspores inside microsporangium ♀ cone scale Fig 30.9

11. Gymnosperm survey Conifers Cycads Ginkgo Gnetophytes

12. Big Tree, Giant Sequoia Sequoiadendron Juniper Juniperus Bristlecone Pine Pinus

13. H.J. Andrews experimental forest, Blue River Oregon

14. Douglas fir canopies … to be continued

15. Maidenhair Tree Ginkgo

16. Cycads

17. Welwitschia Mormon Tea Ephedra