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Plant Tissues

Plant Tissues. Chapter 28 Part 1. Impacts, Issues Drought Versus Civilization. Without plants, we would die – prolonged drought can destroy crops and civilizations. 28.1 Components of the Plant Body.

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Plant Tissues

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  1. Plant Tissues Chapter 28 Part 1

  2. Impacts, IssuesDrought Versus Civilization • Without plants, we would die – prolonged drought can destroy crops and civilizations

  3. 28.1 Components of the Plant Body • The unique organization of tissues in flowering plants is part of the reason why they are the dominant group of the plant kingdom

  4. The Basic Body Plan • Shoots • Aboveground plant parts such as stems, leaves, and flowers • Roots • Structures that absorb water and dissolved minerals, store food, and support the plant • Usually grow down and outward in the soil

  5. Plant Tissue Systems • Ground tissue system • Photosynthesis, storage, and structural support of other tissues • Vascular tissue system • Distributes absorbed water and mineral ions and products of photosynthesis • Dermal tissue system • Covers and protects exposed plant surfaces

  6. Body Plan: Tomato Plant

  7. shoot tip (terminal bud) lateral (axillary) bud young leaf flower node internode dermal tissue node vascular tissues leaf seeds in fruit withered seed leaf (cotyledon) ground tissues stem SHOOTS ROOTS primary root lateral root root hairs root tip root cap Fig. 28-2, p. 476

  8. Animation: Tissue systems of a tomato plant

  9. Eudicots and Monocots • Flowering plants are divided into two classes with tissues organized into different patterns • Eudicots have two cotyledons (seed leaves) • Monocots have one cotyledon

  10. Eudicots and Monocots

  11. A In seeds, two cotyledons (seed leaves of embryo) Flower parts in fours or fives (or multiples of four or five) Leaf veins usually forming a netlike array Pollen grains with three pores or furrows Vascular bundles organized in a ring in ground tissue B In seeds, one cotyledon (seed leaf of embryo) Flower parts in threes (or multiples of three) Leaf veins usually running parallel with one another Pollen grains with one pore or furrow Vascular bundles throughout ground tissue Fig. 28-3, p. 477

  12. Animation: Eudicots and monocots

  13. Introducing Meristems • All plants tissues arise at meristems (regions of rapidly dividing, undifferentiated cells) • Growth in apical meristems at tips of shoots and roots (primary growth) increases length • In some plants, growth in lateral meristems (secondary growth) thickens roots and shoots

  14. Apical and Lateral Meristems

  15. Fig. 28-4a, p. 477

  16. shoot apical meristem (new cells forming) cells dividing, differentiating three tissue systems developing three tissue systems developing cells dividing, differentiating root apical meristem (new cells forming) a Many cellular descendants of apical meristems are the start of lineages of differentiated cells that grow, divide, and lengthen shoots and roots. Fig. 28-4a, p. 477

  17. Fig. 28-4b, p. 477

  18. vascular cambium cork cambium thickening b In woody plants, the activity of two lateral meristems—vascular cambium and cork cambium—result in secondary growth that thickens older stems and roots. Fig. 28-4b, p. 477

  19. 28.2 Components of Plant Tissues • Different plant tissues form just behind shoot and root tips, and on older stem and root parts • Tissue systems are organized as simple tissues (one cell type) or complex tissues (two or more cell types)

  20. Simple Tissues • Parenchyma makes up most primary growth • Functions in secretion, storage, photosynthesis (mesophyll), and tissue repair • Collenchyma supports growing plant parts • Pectin provides flexibility • Sclerenchyma contains lignin for support • Cells (fibers, sclereids) are dead at maturity

  21. Simple Tissues

  22. collenchyma parenchyma Fig. 28-7a, p. 479

  23. lignified secondary wall Fig. 28-7c, p. 479

  24. Complex Tissues: Vascular Tissues • Xylem carries water and ions through the plant • Consists of two types of cells that are dead at maturity: tracheids and vessel members • Lignin-filled secondary walls • Phloem conducts sugars, other organic solutes • Sieve tubes connect end to end at sieve plates • Companion cells load sugars into sieve tubes

  25. Vascular Tissues

  26. one cell’s wall sieve plate of sieve-tube cell pit in wall companion cell a b c parenchyma vessel of xylem phloem fibers of sclerenchyma Fig. 28-8, p. 479

  27. Complex Tissues: Dermal Tissues • Epidermis • Usually a single outer layer of cells that secrete a waxy, protective cuticle • May contain specialized cells that form stomata for gas exchange • Periderm • Replaces epidermis in woody stems and roots

  28. Plant Cuticle

  29. leaf surface cuticle epidermal cell photosynthetic cell Fig. 28-9, p. 479

  30. Flowering Plant Tissues

  31. Studying Plant Parts: Tissue Specimens • Tissue specimens are cut along standard planes

  32. radial: tangential: transverse: Fig. 28-6, p. 478

  33. Tissues in a Buttercup Stem

  34. sclerenchyma (fibers) parenchyma epidermis phloem xylem Fig. 28-5, p. 478

  35. 28.1-28.2 Key ConceptsOverview of Plant Tissues • Seed-bearing vascular plants have a shoot system, which includes stems, leaves, and reproductive parts; most also have a root system • Such plants have ground, vascular, and dermal tissues • Plants lengthen or thicken only at active meristems

  36. 28.3 Primary Structure of Shoots • Inside the soft, young stems and leaves of both eudicots and monocots, the ground, vascular, and dermal tissue systems are organized in predictable patterns

  37. Behind the Apical Meristem • Terminal buds • Main zones of primary growth in shoots • Naked or encased in modified leaves (bud scales) • Form leaves at nodes • Lateral buds (axillary buds) • Dormant shoots in leaf axils • Form side branches, leaves, or flowers

  38. Apical Meristem and Primary Growth

  39. Fig. 28-10 (a-c), p. 480

  40. immature leaf shoot apical meristem a Sketch of the shoot tip in the micrograph at right, tangential cut. The descendant meristematic cells are color-coded orange . b Same tissue region later on, after the shoot tip lengthened above it primary xylem primary phloem pith cortex c Same tissue region later still, with lineages of cells lengthening and differentiating Fig. 28-10 (a-c), p. 480

  41. Fig. 28-10d (1), p. 480

  42. immature leaf youngest immature leaf apical meristem epidermis forming lateral bud forming vascular tissues forming pith Fig. 28-10d (1), p. 480

  43. Fig. 28-10d (2), p. 480

  44. Inside the Stem • Vascular bundles • Multistranded cords of vascular tissues threaded lengthwise through ground tissues of all shoots • Two distinct patterns of vascular bundles • Eudicot stems: Cylinders run parallel with stem, divide ground tissue into cortex and pith • Monocot stems: Bundles distributed throughout ground tissue

  45. Eudicot and Monocot Stems

  46. Fig. 28-11a, p. 481

  47. vessel in xylem meristem cell epidermis cortex vascular bundle pith companion cell in phloem sieve tube in phloem A Stem fine structure for alfalfa (Medicago), a eudicot Fig. 28-11a, p. 481

  48. Fig. 28-11b, p. 481

  49. collenchyma sheath cell air space vessel in xylem epidermis vascular bundle pith sieve tube in phloem companion cell in phloem B Stem fine structure for corn (Zea mays), a monocot Fig. 28-11b, p. 481

  50. Animation: Stem organization

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