1. Plant Evolution Chapter 23

2. Impacts, Issues Video Beginnings and Endings

3. Setting the Stage for Plants  Earth’s atmosphere was originally oxygen free  Ultraviolet radiation bombarded the surface  Photosynthetic cells produced oxygen and allowed formation of a protective ozone layer

4. Invading the Land  Cyanobacteria were probably the first to spread into and up freshwater streams  Later, green algae and fungi made the journey together  Every plant is descended from species of green algae

5. Evolutionary tree for plants Evolutionary Tree for Plants

6. The Plant Kingdom  Nearly all are multicellular  Eukaryotic  Terrestrial  Vast majority are photoautotrophs Energy from sun Carbon dioxide from air Minerals dissolved in water

7. Plant Kingdom  Adaptations to land Well developed tissue Cuticle Stomata Protection of embryo  Alternations of generations Sporophyte  Diploid  Produces spores by meiosis Reproductive structure Develops into new organism without the need to fuse with another reproductive cell

8. Plant Kingdom Gametophyte  Haploid  Produces gametes Egg and sperm Formed by mitosis  Egg and sperm fuse to form zygote Undergoes mitosis Forms sporophyte

9. mitosis zygote (2n) multicelled sporophyte (2n) fertilizationmeiosis gametes (2n) spores (2n) multicelled gametophytes (n) mitosis Diploid Haploid Evolutionary Trend

10. Haploid to diploid dominance Evolutionary Trend

11. sporophyte’s importance gametophyte’s importance green algaebryophytesfernsgymnospermsangiosperms zygote only, no sporophyte

12. 4 Major Groups of Plants  Nonvascular  Seedless Vascular  Gymnosperms  Angiosperms

13. Nonvascular Plants  3 types of plants Hornworts  Symbiotic relationship with cyanobacteria Liverworts Mosses  Peat, true and rock  Sphagnum Great ability to absorb water

14. Peat Mosses

16. Marchantia: A Liverwort

17. Female gametophyte Male gametophyte Marchantia: A Liverwort

19. Moss life cycle Moss Life Cycle

20. Zygote grows, develops into a sporophyte while still attached to gametophyte. Fertilization zygote sperm- producing structure egg- producing structure Diploid Stage Haploid Stage mature sporophyte Meiosis Spores germinate. male gametophyte female gametophyte

21. Nonvascular Plants  Lack specialized means of transporting water, nutrients  Do not have true roots, stems or leaves Have root, stem and leaf like structures  Rhizoids Threadlike cellular structures  Absorb water and nutrients  Anchor gametophytes to substrates

22. Nonvascular Plants Gametophyte  Dominant generation Archegonia  Produces and protects eggs Antheridia  Produce flagellated sperm  Sperm swims to egg and forms embryo - develops into sporophyte - sporophyte derives nutrition from gametophye - produces spores

23. Seedless Vascular Plants  Like bryophytes Live in wet, humid places Require water for fertilization  Unlike bryophytes Sporophyte is free-living and has vascular tissues  Epiphytes Plants live on trees but are not parasitic

24. Seedless Vascular Plants  Vascular tissue  Microphylls 1 strand of vascular tissue  Club mosses, horse tails, whisk ferns  Macrophylls Many strands of vascular tissue  Ferns

25. Seedless Vascular Plants Xylem  Conducts water and dissolved nutrients upwards from the roots  Contain lignin Stronger for support and waterproof Protects from parasites and predators Phloem  Conducts sucrose and other organic compounds throughout the plant

26. Seedless Vascular Plants

27.  Reproduction Moist environment Homosporous Large sporophyte with vascular tissue Gametophyte small and independent

28. Ferns  Most common sporophyte structure Perennial underground stem  rhizome Roots and fronds arise from rhizome Young fronds are coiled “fiddleheads” Mature fronds divided into leaflets Spores form on lower surface of some fronds

29. p.379

30. Fern life cycle Fern Life Cycle

31. Spores are released Sporophyte still attached to gametophyte zygote fertilization Diploid Stage Haploid Stage egg sperm mature gametophyte Spores develop meiosis Spore germinates rhizome sorus

32. Seed-Bearing Vascular Plants  Gymnosperms arose first Cycads Ginkgos Gnetophytes Conifers  Angiosperms arose later Monocots Dicots

33. Adaptations to Land  Root systems  Shoot systems  Vascular tissues  Waxy cuticle

34. Seed-Bearing Vascular Plants  Pollen grains Arise from microspores Develop into male gametophytes Can be transported without water  Seeds Embryo sporophyte inside nutritive tissues and a protective coat Can withstand hostile conditions More water-conserving

35. pine pollen grains Pollen

36. Seed-Bearing Vascular Plants Female reproductive structures that become seeds  Consist of: Female gametophyte with egg cell Nutrient-rich tissue Jacket of cell layers that will form seed coat  Pollination Can occur by wind or by pollinators No external water is needed for fertilization

37. Ovules

38. Gymnosperms  Plants with “naked seeds”  Seeds don’t form inside an ovary  Four groups Conifers Ginkgos Cycads Gnetophytes

39. Gymnosperm Characteristics  Widest known, largest number of living species  Woody trees or shrubs  Most are evergreen  Bear seeds on exposed cone scales  Most produce woody cones

40. Gymnosperm Characteristics  Reproduction Time between pollination and fertilization could take a year or more Male strobili  Sporophyte  Microspores Walled structure protects male gametophyte Become pollen grains Female strobili  Sporophyte  Megaspore Develops within ovule Stays attached to parent plant

41. Pine cones Pine Life Cycle

42. Pine life cycle Pine Life Cycle

43. Gymnosperms  Conifers Evergreens, pines, firs Needle like leaves  Conserve water Thick cuticle Recesses stomata  Monoeicious Tree produces both male and female gametophytes  Pollinated by wind

44. Gymnosperms  Ginkgo bilboa Dioecius Resistant to pollution Pollen tube bursts to release multiflagellated sperm Female trees gives off fowl odor when seeds ripen

45. Gymnosperms  Cycads Dioecius Pollinated by insects Palmlike appearance Strobilus of a “female” cycad

46. Gymnosperms  Gnetophytes Don’t have archegonia Most closely related to angiosperms  Produce nectar Sporophyte of Ephedra

47. Angiosperms  Flowering plants  Dominant land plants  Ovules and (after fertilization) seeds are enclosed in an ovary  Three main groups Magnoliids Monocots Eudicots

48. Angiosperms  Monocots 1 seed coat Flower parts in 3’s or multiples of Herbaceous Parallel veins Scattered bundles in stem Fibrous roots  Eudicots 2 seed coats Flower parts in 4’s or 5’s Woody or herbaceous Net veins Vascular bundles in ring taproot

49. Inside seeds, two cotyledons seed leaves of embryo Usually four or five floral parts (or multiples of four or five) Leaf veins usually in a netlike array Three pores or furrows in the pollen grain surface Vascular bundles organized as a ring in ground tissue Inside seeds, one cotyledon seed leaf of embryo Usually three floral parts (or multiples of threes) Leaf veins usually running parallel with one another One pre or furrow in the pollen grain surface Vascular bundles distributed throughout ground tissue

50. Flower parts Flowering Plant Life Cycle

51. Angiosperms  4 main parts Sepals (calyx)  Protect flower bud  Usually green Petals (corolla)  Vary in shape, size and color Stamen  2 parts filament Anther  Sac-like container  Pollen grains develop

52. Angiosperms  Carpel 3 regions  Stigma Enlarged sticky knob  Style Slender stalk  Ovary Enlarged base encloses 1 or more ovule  Ovule becomes seed  Ovary becomes fruit

53. stamen (microspores form here) carpel (megaspores form here) petal sepal ovule in an ovary

54. Angiosperms  Complete flower Contains all 4 parts  Incomplete flower Missing 1 of the 4 parts  Perfect flower Has both stamen and carpel  Imperfect flower Has either the stamen or carpel

55. Monocot life cycle Monocot Life Cycle

56. Double Fertilization  Distinctive feature of angiosperms  Male gametocyte delivers two sperm to an ovule  One fertilizes egg; other fertilizes a cell that gives rise to endosperm

57. Flowering Plant Life Cycle Double fertilizationMeiosis microspores female gametophyte pollination mitosis without cytoplasmic division two sperm enter ovule Diploid Haploid sporophyte