CHAPTER 34 The Plant Body

1. CHAPTER 34The Plant Body

2. Chapter 34: The Plant Body Vegetative Organs of the Flowering Plant Body Plant Cells Plant Tissues and Tissue Systems Forming the Plant Body Leaf Anatomy Supports Photosynthesis

3. Vegetative Organs of the Flowering Plant Body • Monocots typically have a single cotyledon, narrow leaves with parallel veins, flower parts in threes or multiples of three, and stems with scattered vascular bundles. 3

4. Vegetative Organs of the Flowering Plant Body • Eudicots typically have two cotyledons, broad leaves with netlike veins, flower parts in fours or fives, and vascular bundles in a ring. • Flowering plants that are neither monocots nor eudicots are generally similar in structure to eudicots. Review Figure 34.1 4

5. figure 34-01.jpg Figure 34.1 Figure 34.1

6. Vegetative Organs of the Flowering Plant Body • The vegetative organs of flowering plants are • roots, which form a root system, • stems and • leaves, which form a shoot system. Review Figure 34.2 6

7. figure 34-02.jpg Figure 34.2 Figure 34.2

8. Vegetative Organs of the Flowering Plant Body • Roots anchor the plant and take up water and minerals. 8

9. Vegetative Organs of the Flowering Plant Body • Stems bear leaves and buds. • Lateral buds form branches. • Apical buds produce cells that contribute to stem elongation. 9

10. Vegetative Organs of the Flowering Plant Body • Leaves are responsible for most photosynthesis • their flat blades, oriented perpendicular to the sun’s rays, are well adapted. Review Figure 34.5 10

11. figure 34-05.jpg Figure 34.5 Figure 34.5

12. Plant Cells • Plant cell walls have a structure that often corresponds to special functions of the cell. • Walls of individual cells are separated by a middle lamella common to two neighboring cells; each cell has its own primary wall. Review Figure 34.6 12

13. figure 34-06.jpg Figure 34.6 Figure 34.6

14. Plant Cells • Some cells produce a thick secondary wall. • Adjacent cells are connected by plasmodesmata extending through both cell walls. Review Figures 34.7, 34.8 14

15. figure 34-07.jpg Figure 34.7 Figure 34.7

16. figure 34-08.jpg Figure 34.8 Figure 34.8

17. Plant Cells • Parenchyma cells have thin walls. • Many store starch or lipids • Some others carry out photosynthesis. 17

18. Plant Cells • Collenchyma cells provide flexible support. 18

19. Plant Cells • Sclerenchyma cells provide strength and function when dead. 19

20. Plant Cells • Tracheids and vessel elements are xylem cells that conduct water and minerals after the cells die. Review Figures 34.10 20

21. figure 34-10.jpg Figure 34.10 Figure 34.10

22. Plant Cells • Sieve tube members are conducting cells of the phloem. • Their activities are often controlled by companion cells. Review Figure 34.11 22

23. figure 34-11.jpg Figure 34.11 Figure 34.11

24. Plant Tissues and Tissue Systems • The vascular tissue system conducts water, minerals, and the products of photosynthesis. • The dermal tissue system protects the body surface. • The ground tissue system produces and stores food materials and performs other functions. Review Figure 34.12 24

25. figure 34-12.jpg Figure 34.12 Figure 34.12

26. Forming the Plant Body • The apical–basal pattern and the radial pattern are parts of the plant body plan; • They arise through orderly development. Review Figure 34.13 26

27. figure 34-13.jpg Figure 34.13 Figure 34.13

28. Forming the Plant Body • Plant development differs from animals. • The plant body is modular, and the growth of stems and roots is indeterminate. • Leaves, flowers, and fruits show determinate growth. 28

29. Forming the Plant Body • Meristems are localized regions of cell division. • A hierarchy of meristems generates the plant body. 29

30. Forming the Plant Body • Apical meristems at the tips of stems and roots produce the primary growth of those organs. Review Figure 34.14 30

31. figure 34-14.jpg Figure 34.14 Figure 34.14

32. Forming the Plant Body • Shoot apical and root apical meristems give rise to primary meristems: • protoderm • ground • procambium Review Figure 34.15 32

33. figure 34-15.jpg Figure 34.15 Figure 34.15

34. Forming the Plant Body • In some plants, the products of primary growth constitute the entire plant body. Others show secondary growth. • Two lateral meristems, the vascular cambium and cork cambium, are responsible for secondary growth. Review Figure 34.14 34

35. Forming the Plant Body • The young root has an apical meristem that gives rise to the root cap and three primary meristems, which produce the three tissue systems. • protoderm produces the dermal tissue system • ground meristem produces the ground tissue system • procambium produces the vascular tissue system. Review Figure 34.15 35

36. Forming the Plant Body • Root tips have three overlapping zones: • the zones of cell division, • cell elongation, and • cell differentiation. Review Figure 34.15 36

37. Forming the Plant Body • The dermal tissue system consists of the epidermis, part of which forms root hairs responsible for absorbing water and minerals. Review Figure 34.16 37

38. figure 34-16.jpg Figure 34.16 Figure 34.16

39. Forming the Plant Body • The ground tissue system of a young root is the cortex, whose innermost cell layer, the endodermis, controls access to the stele. 39

40. Forming the Plant Body • The stele, consisting of pericycle, xylem, and phloem, is the root’s vascular tissue system. • Lateral roots arise in the pericycle. • Monocot roots have a central pith region. Review Figure 34.17 40

41. figure 34-17.jpg Figure 34.17 Figure 34.17

42. Forming the Plant Body • The shoot apical meristem gives rise to three primary meristems, with roles similar to counterparts in the root. • Leaf primordia on the sides of the apical meristem develop into leaves. 42

43. Forming the Plant Body • Vascular tissue in young stems is divided into vascular bundles, each containing xylem and phloem. • Pith occupies the center of the monocot stem. • Cortex lies to the outside of vascular bundles in monocot, and pith rays lie between them. 43

44. Forming the Plant Body • Many eudicot stems and roots show secondary growth, in which vascular and cork cambia give rise to secondary xylem and phloem. • As secondary growth continues, wood and bark are produced. Review Figure 34.19 44

45. figure 34-19a.jpg Figure 34.19 – Part 1 Figure 34.19 – Part 1

46. figure 34-19b.jpg Figure 34.19 – Part 2 Figure 34.19 – Part 2

47. Forming the Plant Body • The vascular cambium lays down layers of secondary xylem and phloem. • Living cells within these tissues are nourished by vascular rays. 47

48. Forming the Plant Body • The periderm consists of cork, cork cambium, and phelloderm, all pierced at intervals by lenticels that allow gas exchange. 48

49. Leaf Anatomy Supports Photosynthesis • Mesophyll is the photosynthetic tissue of a leaf. • Veins bring water and minerals to the mesophyll and carry products of photosynthesis to other parts of the plant body. 49

50. Leaf Anatomy Supports Photosynthesis • A waxy cuticle prevents water loss from the leaf, but is impermeable to carbon dioxide. • Guard cells control opening of stomata, leaf openings that allow CO2 to enter but also water to escape. Review Figure 34.23 50