plants (External & Internal Structures)

1. plants (External & Internal Structures) (Part 1)

2. shoot apical meristem terminal bud leaf axillary bud blade vascular tissue petiole node Shoot system internode vascular tissue vascular tissue Root system root hair dermal tissue root apical meristem ground tissue root cap root tip vascular tissue

3. ROOTS

4. Types of root systems Tap root system Fibrous root system

5. Primary Root System Primary Root Secondary Root Tertiary Root

6. Fibrous Root System The primary root is lost and is replaced by numerous adventitious roots arising from the lower part of the stem. These roots are fibrous in appearance , that is, they are slender in form and are more or less equally prominent

7. Elongation region • Cells in this region increase in size, particularly in length The Root Tip Meristematic region • Actively dividing cells in various stages of mitosis Root cap • Produces mucigel for protection, lubrication, water and nutrient absorption

8. Three primary meristems Protoderm • outermost primary meristem – gives rise to epidermis. Ground Meristem • store food and uptake of minerals Procambium • gives rise to stele – central cylinder of vascular tissue where xylem and phloem develop Quiescent Zone • slower or no cell division

9. Maturation region • characterized by the presence of root hairs • is made up of primary tissues that develop from transitional meristems of the elongation region Protoderm epidermis Ground meristem cortex pericycle phloem Procambium vascular cambium xylem

10. Root hairs Increase the surface area for the absorption of water

11. epidermis cortex vascular cylinder Young dicot root Exarch - tetrarch Stele - actinostele

12. cortex endosperm with casparian strip pericycle xylem phloem vascular cambium

13. lateral root arising from pericycle xylem phloem endodermis with casparian strip cortical parenchyma uncutinized epidermis with root hair

14. primary root xylem lateral root Lateral roots develop from the pericycle

15. epidermis cortex endodermis pericycle Monocot root pith xylem phloem root hairs

16. Exarch polyarch Stele actinostele

17. Modified Roots

18. For Support - Brace roots Aerial roots arising from the main stem which penetrates the ground Corn (Zeamays) Pandan(Pandanusodoratissimus)

19. For Support - Prop roots Aerial roots arising from the branches which penetrates the ground Mangrove (Rhizophora sp.) Banyan tree (Ficusindica)

20. For Support – Clinging roots Aerial roots which adhere to some kind of support English ivy (Hedera helix)

21. For Support - Buttress Plant-like extensions from the lower part of the stem Ficus sp.

22. For Reproduction Adventitious buds in root Bog Yellowcress (Rorippapalustris)

23. For Protection Screw pine (Pandanustectorius) Presence of spines

24. For Photosynthesis Green aerial roots Vanda sp.

25. For Food Storage enlarged, fleshy and succulent roots White Radish (Raphanussativus) Carrot (Daucuscarota)

26. For Aeration development of pneumatophores – roots with spongy tissues protruding above the ground Mangrove (Rhizophora sp.)