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Kingdom Plantae Chapter 29 Plant Diversity 1: How Plants Colonized Land

Kingdom Plantae Chapter 29 Plant Diversity 1: How Plants Colonized Land. Plant Evolution – Where did land plants come from?. Closest living relatives to the land plants = Charophytes. Evidence that supports this idea. Biochemical similarity Similarities in cytokinesis

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Kingdom Plantae Chapter 29 Plant Diversity 1: How Plants Colonized Land

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  1. Kingdom PlantaeChapter 29Plant Diversity 1:How Plants Colonized Land

  2. Plant Evolution – Where did land plants come from? Closest living relatives to the land plants = Charophytes

  3. Evidence that supports this idea Biochemical similarity Similarities in cytokinesis Sperm cell ultrastructure Genetic relationships

  4. How did the move onto land happen? • In charophytes a layer of a durable polymer called sporopolleninprevents exposed zygotes from drying out • Sporopollenin is also found in plant spore walls

  5. Movement of plants from water to land Hurdles Advantages • Desiccation • Gas exchange • Support of multicellular structures • Spore/seed dispersal • Reproduction • Unfiltered sunlight • Plentiful CO2 • Soil rich in mineral nutrients • Fewer herbivores • Fewer pathogens

  6. Derived Traits of Land Plants • Apical meristems • Specific areas of cell division at tips of roots & shoots • Multicellular embryos • Retained within tissues of female parent • protection & nourishment • Walled spores in sporangia • Resistant to harsh environments • Carried by dry air • Multicellular gametangia • Archegonia (female) and Antheridia (male) • Alternation of generations

  7. Figure 29.3eApical Meristems Apical meristemof shoot Apical meristems Developingleaves Apical meristemof root Shoot Root Apical meristems of plant roots and shoots

  8. Alternation of Generations • The plant life cycle includes alternation of • Haploid (n) generation – Multicellular Gametophyte • Diploid (2n) generation – Multicellular Sporophyte

  9. Additional terrestrial adaptations Stomata cuticle • Specialized pores for gas exchange • Waxy layer to prevent desiccation

  10. Figure 29.5 The Origin & Diversification of Plants ANCESTRALGREENALGA Liverworts Nonvascularplants(bryophytes) Origin of land plants Land plants Mosses 2 3 1 Hornworts Lycophytes (club mosses,spike mosses, quillworts) Seedlessvascularplants Origin of vascular plants Monilophytes (ferns,horsetails, whisk ferns) Vascular plants Gymnosperms Seedplants Origin of extantseed plants Angiosperms 500 450 400 350 300 50 0 Millions of years ago (mya)

  11. * Small & herbaceous plants * Gametophyte stage is the dominant stage of the lifecycle * Dependent upon water for reproduction

  12. Phylum Hepatophyta- the Liveworts Small, nonvascular, spore producing land plants have a thin, leathery body that grows flat on moist soil or on surface of still water liver – refers to shape of gametophyte Lack stomata

  13. Figure 29.3d Multicellular gametangia Femalegametophyte Archegonia,each with anegg (yellow) Antheridia(brown),containing sperm Malegametophyte Archegonia and antheridia of Marchantia (a liverwort)

  14. Liverworts con’t. Archegonia with egg Sporophyte Stage Foot Seta Capsule(sporangium)

  15. Liverworts con’t. Gemmae Cup Gemmae Asexual reproduction can occur as well……

  16. Marchantia sp. Lifecycle

  17. Phylum Anthocerophyta– the Hornworts • Horn – long, tapered sporophyte • Often first to colonize open spaces w/ moist soil • Symbiotic relationship with N-fixing bacteria

  18. Figure 29.7b Hornworts (Phylum Anthocerophyta) Sporophyte*lacks seta Gametophyte An Anthoceros hornwort species * Rhizoids on underside of gametophyte for anchorage

  19. Anthoceros sp. Lifecycle –Hornwort (Anthocerophyta)

  20. Phylum Bryophyta- the mosses Common to moist forests & wetlands; mountaintops, tundra, deserts Sometimes in sandy soils  retain nitrogen May tolerate cold or dry habitats Cell walls absorb damaging levels of UV radiation

  21. Figure 29.7c Mosses (Phylum Bryophyta) Sporophyte (takes months to grow) Capsule Seta Foot Gametophyte Polytrichum commune, hairy-cap moss

  22. Figure 29.6 “Bud” Sperm Protonemata(n) Antheridia Malegametophyte (n) Key Haploid (n)Diploid (2n) “Bud” Egg Spores Gametophore Sporedispersal Archegonia Femalegametophyte (n) Rhizoid Peristome Sporangium Seta FERTILIZATION Capsule(sporangium) (within archegonium) MEIOSIS Zygote(2n) Maturesporophytes Embryo Foot Archegonium 2 mm Youngsporophyte(2n) Femalegametophyte Capsule withperistome (LM)

  23. Bryophytes Ruled the Land for 100 million years……..until the Seedless Vascular Plants

  24. Similarities & Differences between Bryophytes and Seedless Vascular Plants Similarities Differences • Cuticle • Alternation of Generations • Stomata • Dependent upon water for reproduction • Dominant generation = Sporophyte • Branched Sporangia • Vascular Tissues • Xylem • Phloem • Increase in height • Primary & secondary growth • Organs • Leaves, stems, and roots

  25. Seedless vascular plant adaptations • Branched Sporangia • Vascular Tissues Xylem Phloem

  26. Seedless vascular plant adaptations con’t. • Leaves • Sporophyll modified leaf w/ sporangia • Sori • Strobili • Homosporous • Single spore type  bisexual gametophyte • Heterosporous • Megasporangium • Megaspore  female gametophyte • Microsporangium • Microspore  male gametophyte Microphyll Megaphyll

  27. Phylum Lycophyta- the Lycophytes Quillwort - heterosporous Spike “Moss” Club “Moss” - heterosporous - homosporous Lycopodium sp. * Epiphytic* Microphylls

  28. P: Lycophytacon’t.- life cycle

  29. Phylum Monilophyta Ferns Horsetails Whisk Ferns Equisetum sp. Psilotum sp.

  30. Phylum Monilophyta- the ferns - Underside of frond/megaphyll - note sori (mostly homosporous) Fiddle Head- sporophyte - gametophyte

  31. Figure 29.11 Fern Life cycle Key Haploid (n)Diploid (2n) Antheridium Spore(n) Young gametophyte Sporedispersal MEIOSIS Rhizoid Undersideof maturegametophyte(n) Sporangium Sperm Newsporophyte Sporangium Archegonium Egg Maturesporophyte(2n) Zygote(2n) FERTILIZATION Sorus Gametophyte Fiddlehead (young leaf)

  32. P: Monilophytacon’t. • The Horsetails • Equisetum sp. • “Scouring Rush” • Separate vegetative & reproductive stems • Homosprous • Air canals • Rings of small leaves

  33. P: Monilophytacon’t. • The Whisk Ferns • Note dichotomous branching stems  no roots • 3 fused sporangia  yellow knobs • homosporous

  34. Importance of seedless vascular plants • Increased growth & photosynthesis  • removed CO2 from the atmosphere • contributed to global cooling at the end of the Carboniferous period • The decaying plants of these Carboniferous forests eventually became coal

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