Understanding Plant Roots, Stems, and Leaves

1. Chapter 23Roots 23:2

2. Roots – anchors plant into the ground and transports materials to the plants body • 2 types • Tap – primary root that grows long and thick. • Fibrous – branching, where no single root grows longer than the rest, covers a large surface area holding soil in place. fibrous adventures primary root

3. II. Roots structure and Growth • A. 3 Tissue systems • 1. Dermal – Epidermis type found on the outside of a root. • 2. Vascular – Central cylinder, xylem and Phloem. • 3. Ground – Cortex, between dermal and vascular

4. DERMAL

5. B. Root system plays a large role in water and mineral transport along with protection and absorption. 1. Root hairs – produce large surface area in soil through which water can enter the plant. 2. Cortex- spongy layer of ground tissue. 3. Endodermis – covers the roots vascular system. 4. Vascular Cylinder – center of the root. 5. Root Cap – covers and protects the apicalmeristem cells that grow the root in length. It secretes a slippery substance that lubricates the progress of the root through the soil.

6. Vascular, cortex, endodermis, epidermis

8. III Root Function • A. Functions • 1. Anchor and support plant • 2. Absorbs water which travels up the xylem vascular tissue to the plants body. • 3. Absorbs dissolved nutrients such as carbohydrates from photosynthesis and are transport throughout the plants body in the phloem vascular tissue.

9. Stems

10. Vascular Tissue • Xylem – vascular tissue that transports water and minerals up into the plants body. • Phloem – vascular tissue that transports food, mainly sugar throughout the body of the plant moving in many directions.

11. Stems 23-3 Structure and Function A. 3 Functions 1. Produce Leaves, branches and flowers. 2. Hold leaves up to sunlight. 3. Transport substances between root and leaves.

12. B. Structure • 1. Nodes – where leaves are attached • 2. Internode – region between the nodes. • 3. Buds – contains under developed tissue that can produce new stem and leaves.

14. C. Monocot and Dicot Stems • 1. Monocot stems – scattered vascular bundles, parallel venation on leaves, herbaceous stems. • 2. Dicot stems – vascular bundles are arranged in a cylinder, branched venation on leaves, woody stems.

15. Monocot cross section

16. Examples of Monocot plants

17. Dicot cross section

18. Dicot versus Monocot

19. Primary Growth of stems • A. Growth only on the tips of roots and stems is called primary growth. • 1. This growth is produced by cell division in the apical meristem. This growth takes place in all seed plants.

20. Secondary growth of stems • A. The method of growth in which stems increase in width is called secondary growth. • 1. Conifers and dicots secondary growth takes place in the lateral meristematic tissues called the vascular cambium and cork cambium. • A. vascular cambium produce vascular tissue and cork cambium produce outer coverings of stems.

21. Leaves

22. I. Leaves 23-4 A. Leaves are the main organ of a plant that conducts photosynthesis, making glucose, by capturing sunlight. B. Leaves have special cells (chlorophyll) that allow it to perform this chemical reaction.

24. A. Structure and Function • 1. Mesophyll – leaf ground tissue • A. Upper Epidermis -covers top and is sometimes covered with a cuticle. • B. Cuticle – waxy covering on the surfaces of some leaves to protect and prevent drying out. • 2. PalisadeCell Layer– Under the upper epidermis, closely packed cells, absorb light, lots of chlorophyll.

26. 3. Spongy Cell Layer – below the palisade layer, contains many air spaces for gas exchange. Also where the vascular tissue is found. • 4. Stomata – pore like openings underside of the leaf (lower epidermis) that allows carbon dioxide and oxygen to diffuse into and out of the leaf. • 5. Guard cells- surround stomata, control the opening and closing of the stomata by responding to changes in water pressure. • 6. Lower Epidermis – Bottom of leaf that contains stomata’s

28. Stomata’s and guard cells