Ch29_Lecture-Spr11

Ch29_Lecture-Spr11 - 29 The Evolution of Seed Plants 29 The...

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The Evolution of Seed Plants 29
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29 The Evolution of Seed Plants • 29.1 How Did Seed Plants Become Today’s Dominant Vegetation? • 29.2 What Are the Major Groups of Gymnosperms? • 29.3 What Features Contributed to the Success of the Angiosperms? • 29.4 How Do Plants Support Our World?
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29.1 How Did Seed Plants Become Today’s Dominant Vegetation? Late in Devonian, some plants developed secondary growth Thickened woody stems of xylem The first species with secondary growth were progymnosperms seedless vascular plants, now extinct http://www.futura-sciences.com/uploads/tx_oxcsfutura/comprendre/d/images/600/fig_1213.jpg
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29.1 How Did Seed Plants Become Today’s Dominant Vegetation? Earliest seed plants from Devonian These seed ferns were also woody Clades of seed ferns are known only as fossils Two of the clades are basal to surviving seed plants http://www.palaeos.com/Plants/Lists/Glossary/Images/SeedFern.jpg
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Figure 29.1 The Fossil Record of Seed Plants and Some of Their Extinct Seedless Relatives
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29.1 How Did Seed Plants Become Today’s Dominant Vegetation? Surviving seed plants fall into two groups: Gymnosperms: conifers and cycads Angiosperms: flowering plants
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Figure 29.2 The Major Groups of Living Seed Plants
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29.1 How Did Seed Plants Become Today’s Dominant Vegetation? Gametophyte generation is reduced even further than it is in ferns Haploid gametophyte develops partly or entirely attached to sporophyte Nonvascular – Mosses Vascular, seedless – Ferns Vascular, seed plants
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Figure 29.3 The Relationship between Sporophyte and Gametophyte (Part 1)
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Figure 29.3 The Relationship between Sporophyte and Gametophyte (Part 2)
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29.1 How Did Seed Plants Become Today’s Dominant Vegetation? Only earliest gymnosperms had swimming sperm Without swimming sperm, seed plants were independent of water for sexual reproduction Major advantage for terrestrial lifestyle http://www1.fccj.cc.fl.us/dbyres/pollen400_small1.jpg Pine pollen germinating to produce a pollen tube that will carry the male gamete to the egg.
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29.1 How Did Seed Plants Become Today’s Dominant Vegetation? Seed plants are heterosporous Produce two types of spores One becomes female gametophyte, one becomes male gametophyte Seed plants form separate megasporangia and microsporangia http://bio1151.nicerweb.com/doc/c lass/bio1151/Locked/media/ch30/ 30_03OvuleToSeedA.jpg
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The Seed Plants Megaspores develop into female (mega-)gametophytes Retained within megasporangia and dependent on sporophyte Only one of the meiotic products in megasporangium survives Surviving haploid nucleus produces a multicellular female (mega-)gametophyte Retained within megasporangium, megagametophyte matures into egg and is eventually fertilized next generation (sporophyte) http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory/files/Bio%20102/Bio%20102%20lectures/Seed%20Plants
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Seed Plant Reproduction Sporophyte Meiosis Fertilization Seed Megaspores Microspores Megagametophyte Microgametophyte (pollen grain) Sperm Eggs Zygote Diploid ( 2n )
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Ch29_Lecture-Spr11 - 29 The Evolution of Seed Plants 29 The...

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