Plant Structure & Organization

1. Plant Structure & Organization

2. Structure vs. Function Cabomba

3. Review of Life Hierarchy • Cells • Tissues • Organs • Systems

4. Two Basic Systems • Root System—Functions in obtaining water & minerals from the soil; found underground (usually) • Shoot System—Obtaining CO2 from the air & obtaining light; carrying out photosynthesis; found above ground (usually) • Systems are interdependent

6. Three Main Organs of Plants • Roots—absorb water and minerals; anchor the plants • Stems—responsible for growth of the plant; holds leaves; transports materials between leaves and roots • Leaves—site of photosynthesis; reproduction--flowers are modified leaves

8. Types of Root Systems • Fibrous Root Systems • Mat of thin roots • Increases plant’s exposure to water • Anchors plant in the ground • Holds topsoil in place; prevents erosion • Associated with monocots

9. Types of Root Systems • Taproot System • One large, vertical root • Often store food (carrot, turnips, beets) • Really long in desert plants • Associated with dicots

10. Root Facts • Root hairs increase surface area for water absorption; extensions of root epidermis • Adventitious Roots (extra roots)—roots that grow above ground; corn for example—above ground roots are used to “prop” up the plant

11. Types of Shoot Systems • Vegetative—leaf bearing • Reproductive—flower bearing

12. Stem Anatomy • Node—point at which leaves are attached • Internodes—Stem segments between nodes

13. Stem Anatomy • Axillary bud—Can form vegetative branch; angle between stem & leaf; most are dormant • Terminal bud—located at tip of stem; site of stem growth

14. Stem Growth • The presence of the terminal bud inhibits growth of axillary buds therefore there is apical dominance. • This increases a plant’s exposure to light. • Removing terminal bud will stimulate growth of axillary budy.

15. Modified Stems Stolons; Rhizomes; Tubers; Bulbs

16. Leaf Anatomy • Blade—Flattened part • Petiole—stalk of leaf; joins to node

17. Modified Leaves

18. Three types of tissues in plant organs • Dermal—single layer of cells to cover and protect • Vascular—continuous throughout plant; transport materials between roots and shoots • Ground tissue—All other tissue; functions in photosynthesis, storage & support.

19. Vascular Tissue • Xylem—conducts water & minerals from roots to the shoot; against gravity • Phloem—transports sugars manufactured in shoot to non-photosynthetic areas (roots; fruits, etc.)

20. Xylem • Composed of tracheids & vessel elements; elongated cells • Dead at maturity • Remaining cell walls provide a conduit through which water can flow

21. Phloem • Composed of sieve-tube members and companion cells • Sieve tubes are alive at maturity; lack nucleus, ribosomes, and vacuole • Companion cells connect to sieve tubes by plasmodesmata; their nuclei & ribosomes serve sieve tubes.

23. Types of Plant Cells • Parenchyma • Thin & flexible primary cell walls; lack secondary walls • “Typical” plant cells • Perform most metabolic function of plants • Developing plant cells are parenchyma cells

24. Types of Plant Cells • Collenchyma • Have thicker primary walls; no secondary walls • Supports young parts of plant shoot without restraining growth • “Strings” of celery are collenchyma

25. Types of Plant Cells • Sclerenchyma • Thick secondary walls • Cannot elongate • Occur in regions where growth has stopped • For support; many dead at maturity • Vessel elements & tracheids are sclerenchyma cells • Hemp & flax (rope & linen) are sclerenchyma