The Land Plants. Chapter 23 Part 2

Transcription

1 The Land Plants Chapter 23 Part 2

2 23.5 Ancient Carbon Treasures In the Carboniferous, plants with ligninreinforced tissues flourished, died, and became compacted into coal, a nonrenewable fossil fuel Lepidodendron, a Carboniferous lycophyte

3 Energy from the Carboniferous Forest

4 stem of a giant lycophyte (Lepidodendron), which grew 40 meters (131 feet) tall Medullosa, one of the early seed plants stem of a giant horsetail (Calamites), which was almost 20 meters (66 feet) tall Fig a, p. 378

5 Fig b, p. 378

6 Key Concepts Seedless Vascular Plants Lycophytes, whisk ferns, horsetails, and ferns have vascular tissues but do not produce seeds A large spore-producing body that has internal vascular tissues dominates the life cycle As with bryophytes, sperm swim through water to reach eggs

7 23.6 Seed-Bearing Plants Seeds and pollen allowed gymnosperms and angiosperms (flowering plants) to survive and thrive in drier habitats

8 Modified Spores Microspores become sperm-producing male gametophytes (pollen grains) Megaspores develop into egg-producing female gametophytes inside ovules

9 Pollen Seed plants release pollen grains which allow fertilization to occur even in the absence of environmental water

10 pine pollen grains p. 379

11 Seeds A seed is a mature ovule Includes nutritive tissue and a tough seed coat that protects the embryo sporophyte inside the seed from harsh conditions

12 Human Use of Seed Plants Humans depend heavily on cultivated seed plants and have contributed to the widespread dispersal of seed plants that they favor Food crops Lumber and wood product Drugs and medicines Fabrics and dyes

13 Edible Flowering Plants

14 Fig a, p. 379

15 Fig b, p. 379

16 Fig c, p. 379

17 Fig d, p. 379

18 23.7 Gymnosperms Plants With Naked Seeds Gymnosperms Vascular seed plants with naked seeds One of the two modern lineages of seed plants Gymnosperms include conifers (such as pines), cycads, ginkgos, and gnetophytes

19 Some Gymnosperms

20 Fig a, p. 380

21 Fig b, p. 380

22 Fig c, p. 380

23 Fig d, p. 380

24 Fig e, p. 380

25 Fig f, p. 380

26 Fig g, p. 380

27 Fig h, p. 380

28 Gymnosperm Life Cycle Gymnosperms release pollen and seeds Ovules form in in strobili or, in the case of conifers, in woody cones

29 Conifer Life Cycle: Ponderosa Pine

30 I Seed is released, germinates, and the embryo grows and develops into a new sporophyte. spermproducing cell H Ovule develops into a mature seed. pollen tube F Pollen grain matures into male gametophyte. Two nonflagellated sperm nuclei form as pollen tube grows through ovule tissue. seed coat embryo nutritive tissue A A female cone has many scales, each with two ovules, on its upper section through one surface. ovule (the red cut in the diagram to the left) surface view of female cone scale B A male cone has many scales, each housing a pollen sac. surface view of male cone scale G One sperm nucleus fertilizes the egg, forming a zygote. Diploid Stage fertilization Haploid Stage E Pollination: wind deposits pollen grain on seed cone. eggs (view inside ovule) female gametophyte ovule section through pollenproducing sac ( red cut) meiosis D Microspores form by meiosis, develop into pollen grains. C Megaspores form by meiosis; one develops into the female gametophyte. Fig , p. 381

31 Animation: Pine life cycle

32 23.8 Angiosperms The Flowering Plants Angiosperms are the most diverse plant lineage and the only plants that make flowers and fruits In the Mesozoic, angiosperms began adaptive radiation to all land and many aquatic habitats

33 Adaptive Radiation of Angiosperms

34 Keys to Angiosperm Success Short life cycles and rapid growth Specialized reproductive structures (flowers) Specialized pollination and dispersal structures Wind and animal pollinators Fruits that float or stick Seeds that survive animal digestive tracts

35 Specialized Angiosperm Structures A flower is a specialized reproductive shoot Seeds develop inside the ovaries (chambers that enclose ovules) of flowers After fertilization, an ovary becomes a fruit

36 Flower Structures

37 petal stamen (microspores form here) carpel (megaspores form here) sepal ovule in an ovary Fig , p. 382

38 Pollination and Coevolution Pollinators Animals (such as insects that feed on pollen) move pollen grains from male parts of one flower to female parts of another Coevolution Over time, plants and their animal pollinators jointly evolved; changes in one exerts selection pressure on the other

39 Flowering Plant Diversity

40 Fig a, p. 383

41 Fig b, p. 383

42 Fig c, p. 383

43 Fig d, p. 383

44 Fig e, p. 383

45 Fig f, p. 383

46 Fig g, p. 383

47 water star Amborella lilies anise magnoliids monocots eudicots basal groups Fig g, p. 383

48 23.9 Focus on a Flowering Plant Life Cycle Flowering plants form eggs in ovaries and pollen in stamens Flowering plants make fruits containing seeds which supply their embryo sporophytes with endosperm, a nutritive tissue

49 Life Cycle: Lilium

50 The pollen tube enters an ovule. One sperm will fertilize the egg, one will fertilize the endospermproducing cell. seedling seed coat embryo (2n) endosperm (nutritive tissue) A a flowering stem of the mature sporophyte (2n) pollen sac, where each one of many cells will give rise to microspores (line of cut of diagram at left) ovary Pollen is released. cell in ovule that will give rise to a megaspore seed double fertilization Diploid Stage E meiosis meiosis Haploid Stage B C D Pollination and Microspores pollen tube formation: form, then develop into pollen grains. male gametophyte pollen tube sperm (n) sperm (n) cell from which endosperm will form egg female gametophyte ovules inside ovary Four megaspores form. Three disintegrate. One undergoes three rounds of mitosis without any cytoplasmic division. Nuclei migrate and cell walls form. The resulting female gametophyte includes the egg and a cell with two nuclei that will form endosperm. Fig , p. 384

51 The pollen tube enters an ovule. One sperm will fertilize the egg, one will fertilize the endospermproducing cell. E seedling seed coat embryo (2n) endosperm (nutritive tissue) seed Diploid Stage double fertilization Haploid Stage D Pollination and pollen tube formation: male gametophyte pollen tube sperm (n) sperm (n) pollen sac, where each one of many cells will give rise to microspores (line of cut of diagram at left) ovary A a flowering stem of the mature sporophyte (2n) B meiosis Microspores form, then develop into pollen grains. Pollen is released. cell from which endosperm will form egg female gametophyte C meiosis ovules inside ovary cell in ovule that will give rise to a megaspore Four megaspores form. Three disintegrate. One undergoes three rounds of mitosis without any cytoplasmic division. Nuclei migrate and cell walls form. The resulting female gametophyte includes the egg and a cell with two nuclei that will form endosperm. Stepped Art Fig , p. 384

52 Animation: Monocot life cycle

53 23.10 The World s Most Nutritious Plant Botanists use knowledge of plant biology and genetics to find new ways to feed a hungry world Example: Alejandro Bonifacio studies quinoa, a nutritious native South American grain

54 Alejandro Bonifacio and Genetically Modified Quinoa

55 Key Concepts Seed-Bearing Vascular Plants Gymnosperms and, later, angiosperms radiated into higher and drier environments Both produce pollen and seeds Nearly all crop plants are seed plants In angiosperms, flowers and fruits further enhanced reproductive success

56 Summary: Plant Evolutionary Trends

57 Bryophytes Seedless vascular plants Gymnosperms Angiosperms Nonvascular Vascular tissue present Vascular tissue present Vascular tissue present Haploid dominance Diploid dominance Diploid dominance Diploid dominance Water required for fertilization Water required for fertilization Seedless Seedless Naked seeds whisk ferns, liverworts mosses club mosses, horsetails, hornworts spike mosses ferns Pollen grains; water not required for fertilization gnetophytes, ginkgos, conifers, cycads Seeds form inside an ovary that develops into a fruit monocots, dicots, magnoliids, basal groups ancestral alga Fig , p. 386

58 Animation: Flower parts

59 Animation: Pinus cones

60 Video: Beginnings and endings