42.1 - How Are Plant Bodies Organized; How Do They Grow? p. 860

1. Chapter #42 – Plant Anatomy & Nutrient Transport • 42.1 - How Are Plant Bodies Organized; How Do They Grow? p. 860 • 42.2 - The Tissues and Cell Types of Plants? p. 862 • 42.3 - The Structures, Functions of Leaves, Roots, & Stems? p. 865 • 42.4 - How Do Plants Acquire Mineral Nutrients? p. 873 • 42.5 - How Do Plants Move Water Upward from Roots to Leaves? p. 876

2. Plant Anatomy Systems and Tissues • How Are Plant Bodies Organized, and How Do They Grow? • Flowering Plants Consist of a Root System and a Shoot System. • As Plants Grow, Meristem Cells Give Rise to Differentiated Cells.

3. Herbaceous Plants • Soft-bodied plants with flexible stems. • Most are annual (live only one year). • Exhibit primary growth. • e.g. lettuce, beans, grasses

4. Woody Plants • Plants with hard, thickened, woody stems • Most are perennial (live many years) • Exhibit primary and secondary growth • e.g. trees, bushes

5. Leaves

6. Types of Leaves • Simple leaves have a single blade on one petiole. • Compound leaves have multiple leaflets on one petiole.

7. Leaf Parts • Two major parts to the leaf: • Blade • Petiole

8. Leaf Microanatomy • Epidermis and cuticle slow evaporation. • Guard cells regulate gas exchange. • Mesophyll carries out photosynthesis • Veins bring water, move sugars.

9. Photosynthesis • The purpose of photosynthesis is to produce organic (carbon-based) molecules (such as sugars). • The plants use these molecules for two purposes: • As an energy source • As building material

10. Stop and think: • On a piece of paper, list plant leaves or products of plant leaves that you have used in the past few days. • What qualities of the leaves made them useful?

11. Roots

12. Types of Root Systems • Taproot systems are found in dicots, and consist of a main root with lateral branches. • Fibrous root systems lose the primary root, which is replaced by many smaller roots.

13. Root Anatomy • Parts of a Root: • Root cap • Root meristem • Zone of elongation • Zone of maturation

14. Root Anatomy: Epidermis • Root epidermis lacks a cuticle, and is porous. Usually has many root hairs. • Water enters through membranes of epidermal cells or through spaces between cells.

15. Root Anatomy: Cortex • The cortex layer is made up of parenchyma cells. • Sugars are linked to make starch for food storage. • Endodermis separates the cortex from the vascular cylinder.

16. Root Anatomy: Vascular Cylinder • Casparian strip around endodermis cells controls water movement. • Pericycle: layer of parenchyma cells, inside of endodermis, from which branch roots can arise.

17. Root Anatomy: Vascular Cylinder • Vascular Cylinder contains: • Phloem for moving sugars. • Xylem for moving water and dissolved minerals.

18. Stop and think: • On your own paper, list any roots that you have used in the past few days. • What qualities of the roots made them useful?

19. Stems

20. Stems: Epidermis • In herbaceous plants and young woody plants, the stem is covered with epidermis. • Epidermis secretes cuticle, has stomata, and may be photosynthetic.

21. Stems: Cortex and Pith • Cortex layer contains parenchyma cells and vascular bundles. • Pith makes up the center of the stem, and is absent in hollow stems.

22. Stems: Vascular Tissue • Vascular bundles are in the cortex. • While primary xylem and phloem are made by the apical meristem, secondary xylem and phloem come from the vascular cambium, another meristem tissue.

23. Trunk: Primary Growth • Primary Growth is primarily vertical. • This kind of growth gives the plant its height.

24. Trunk: Secondary Growth • Secondary growth is seen in woody plants. • This kind of growth produces stronger, thicker stems from the vascular cambium and cork cambium. • Horizontal Growth

25. Wood and Bark • Xylem makes up the wood of trees and shrubs. • Live phloem cells form the green bark. • Dead cork cells make up the bark.

26. Annual Rings • Trees in temperate zones grow at different rates in different seasons, causing annual rings to form. • In some parts of the tropics, if seasons vary little, tree rings are indistinct.

27. Stop and think: • On your own paper, list any stems or products of stems you have used in the last few days. • What qualities of these stems made them useful?

28. Meristem Cells • Meristem cells are undifferentiated cells; able to divide as long as the plant lives. • Apical meristems are located at tips of roots and shoots.

29. Meristem Cells • Differentiated cells are mature cells specialized for a specific function. • Derived from meristem cells that lose the ability to divide. • Usually do not divide. • Example: vessel elements and tracheids of xylem.

30. Meristem Cells • Meristems allow plants to grow throughout their lives. • Primary growth occurs by division of apical meristem cells and differentiation of their daughter cells. • Responsible for growth in length of roots and shoots of all plants.

31. Meristem Cells • Secondary growth occurs by division of lateral meristem cells and differentiation of their daughter cells. • Responsible for an increase in diameter of roots and shoots of most conifers and dicots. • Lateral meristems or cambia (singular, cambium) run parallel to the long axis of roots and shoots.