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CHARACTERISTICS OF PLANTS:

CHARACTERISTICS OF PLANTS:. Eukaryotic Cells Autotrophic and Multicellular Cell Walls Contain Cellulose Alternation of Generation Embryonic Development. More than 280,000 species of plants inhabit Earth today.

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CHARACTERISTICS OF PLANTS:

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  1. CHARACTERISTICS OF PLANTS: • Eukaryotic Cells • Autotrophic and Multicellular • Cell Walls Contain Cellulose • Alternation of Generation • Embryonic Development

  2. More than 280,000 species of plants inhabit Earth today. • Land plants (including the sea grasses) evolved from a certain green algae, called charophytes

  3. Spirogyra, a model chlorophyte

  4. CHALLENGES FACED BY PLANTS FOR LIFE ON LAND • Obtaining enough water • Transporting water and dissolved • substances to other parts of the plant body and transporting the products of photosynthesis to other parts of the plant that don't conduct photosynthesis

  5. Preventing excessive loss of water • by evaporation • Maintaining an extensive moist • surface for gas exchange • Supporting a large plant body against • gravity • Carrying out reproduction when there • is little water

  6. Lastly, withstanding the extreme • fluctuations in temperature, • humidity, wind, and light which • are moderated in water due to • its high heat capacity

  7. Land Plants Evolved from Green • Algae. • Common Characteristics: • Rose-shaped complexes for cellu- • lose synthesis • Peroxisome enzymes • Structure of flagellated sperm • Formation of a phragmoplast

  8. Charophyceans: Chara (top), Coleochaete orbicularis (bottom)

  9. Several Features of Land Plants Differ From Those of Green Algae • Multicellular sex organs with an outer layer of jacket cells • Cuticles on leaves

  10. Derived Traits of Land Plants (These traits are absent in the charophyceans – next four slides)

  11. Apical Meristems of Plant Shoots and Roots

  12. Alternation of Generations: a Generalized Scheme

  13. Multicelllular Gametangia: Archegonium of Marchantia (left), Antheridium of a hornwort (right)

  14. Multicellular Dependent Embryos: Marchantia (left), Shepherd's purse (right)

  15. Walled Spores Produced In Sporangia Cooksonia, a Vascular Plant of the Silurian Period

  16. Leaves of VascularPlants

  17. There are four main groups of land plants: • Bryophytes • Pteridophytes • Gymnosperms • Angiosperms – 90% of all plants

  18. Representatives of theFour Major Groups of Plants

  19. There are four great episodes in the evolution of land plants: • the origin of bryophytes from algal ancestors • the origin and diversification of vascular plants • the origin of seeds • the evolution of flowers

  20. p. 578

  21. Some Highlights of Plant Evolution 140 mya 360 mya 420 mya 475 mya

  22. Reduction in the Size of the Gametophyte

  23. Bryophytes Liverwort Liverwort Hornwort Moss

  24. Moss with Sporophytes Gametophytes

  25. Liverwort, Marchantia Antheridia Archegonia

  26. Hornwort – a Characteristic Bryophyte

  27. Moss (Polytrichum) Life Cycle

  28. The life cycle of Polytrichum, a moss

  29. Pteridophytes Club Moss Whisk Fern Fern Horsetail

  30. Whisk Fern, Psilotum

  31. Club Moss

  32. Club Moss in Olympic National Forest – WA State

  33. Club Moss in Olympic National Forest

  34. Club mosses (Lycopodium) have microphylls, with single veins

  35. Horsetail Horsetails and the other seedless vascular plants have highly branched vascular systems called megaphylls.

  36. Fern sporophyll, a leaf specialized for spore production

  37. Fern Sori (clusters of sporangia)

  38. Sporophylls • modified leaves with sporangia • Most seedless vascular plants • Are homosporous, producing one type of spore that develops into a bisexual gametophyte sporangium > single > bisexual > eggs and sperm type of gametophyte spore

  39. All seed plants and some seedless vascular plants • Are heterosporous, having two types of spores that give rise to male and female gametophytes megaspore > female gametophyte > eggs microspore > male gametophyte > sperm

  40. Fern Life Cycle

  41. The Life Cycle of a Fern

  42. The first seed plants evolved about 360 million years ago, near the end of the Devonian Period. • A seed consists of a plant embryo packaged along with a food supply within a protective coat.

  43. The Reduced Gametophyte of Seed Plants are Protected in Ovules and Pollen Grains

  44. From Ovule to Seed

  45. Phylum Ginkgophyta The Gingko (biloba) tree is a “living fossil” and has been on the earth virtually unchanged for at least 150 million years. It produces “naked” seeds, as do all other gymnospernms.

  46. Seeds Female Gingko

  47. The Ginkgo Tree

  48. Male Female

  49. Sago Palm or Cycad, a gymnosperm

  50. Sago Palm or Cycad Cones Figure 24.19

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