Ch 35 Introduction to Plants

1. Ch 35 Introduction to Plants Kingdom: Plantae • Cell wall • Autotroph (photosynthesis) • Multicellular

2. Agenda • History of Life – Open Note Quiz • Powerpoint on Class Page for Review • Independent Plant Notes • Class Discussion HW: • Finish Flower Worksheets • The Great Plant Escape

3. Two Types Land Plants • Angiosperms(flowering plants) • ~90% plants • Produce seeds within a fruit • Examples: • Grasses • Gymnosperms (naked seeds) • Early plants • Examples • Ferns • Conifers

5. Plant Organization

6. I. Plant Organs • Above ground • Stems, leaves Shoot system • Underground (usually) • Roots Root system

7. Roots • Anchors plant, absorbs H2O & minerals, stores sugars/starches • Root hairs – tiny extensions of epidermal cells, increase surface area for H2O and mineral absorption • Mycorrhizae: fungus + plant root symbiotic relationship Root hairs

8. Fibrous Roots Taproots • Mat of thin roots spread just below surface • Shallow • Increased surface area • One thick, vertical root • Many lateral (branch) roots • Firmly anchors • Stores food Taproot (carrot) Fibrous Root (scallion)

9. Modified Roots

10. Mangrove Forest in Florida

11. Function: display leaves • Terminal bud: growth concentrated at top end of stem • Secretes hormone to prevent growth of axillary buds; growth directed upward, toward light • Axillary buds – located in V between leaf and stem; forms branches (lateral shoots) • Pinching/pruning – removing terminal bud

12. Modified stems • Runner or stolin • Aspen, strawberries, grass • Grow on surface • For asexual reproduction • Rhizome • Iris, ginger, potato, onion • Grow underground • Store food & DNA for new plant • Tuber: end of rhizome • Bulb – underground shoot • Onion • storage leaves

13. Leaves • Function: Photosynthetic organ blade petiole

14. Modified leaves

15. II. Plant Tissues

16. A. Dermal Tissue • Single layer, closely packed cells that cover entire plant • Protect against water loss & invasion by pathogens (viruses, bacteria) • Cuticle: waxy layer

17. B. Vascular Tissue • Continuous throughout plant • Transports materials between roots & shoots • Xylem & Phloem

18. C. Ground Tissue • Anything that isn’t dermal or vascular • Function: storage, photosynthesis, support • Pith: inside vascular tissue • Cortex: outside vascular tissue

19. III. Cell Types • Xylem • Conducts H2O and minerals up from root • Dead, tubular, elongated cells • Phloem • Conducts sugar & organic compounds from leaves to other parts of plant • Living cells aid movement of sugar • 2 Cell Types: sieve tubes, companion cells

20. Xylem Phloem

21. Plant Growth Types of Flowering Plants: • Annuals – 1 year life cycle • Biennials – 2 years • Perennials – continuous life cycle for many years Meristem: perpetually embryonic tissues • Cells divide for plant growth • Apical meristem: growth at tips of roots & buds of shoots; cause primary growth (increase length) • Lateral meristem: growth thickens shoots and roots; secondary growth

22. Primary and Secondary Growth

23. Root Anatomy Root Hairs Zone of Maturation: primary growth becomes functionally mature Zone of Elongation: cells elongate; push root tip ahead Zone of Cell Division: apical meristem; new cells produced (mitosis) Root cap: protects meristem as it pushes through soil

24. Leaf Anatomy • Epidermis of underside interrupted by stomata (pores), flanked by guard cells (open/close stomata) • Mesophyll: ground tissue between upper/lower epidermis • Parenchyma: sites of photosynthesis

25. Secondary Growth = increase diameter • Involves lateral meristems • Vascular cambium: produces secondary xylem (wood) • Cork cambium: produces tough covering that replaces epidermis • Bark = all tissues outside vascular cambium

26. Primary and Secondary Growth of a Stem Secondary phloem Primary and secondary growth in a two-year-old stem Vascular cambium Cork cambium Late wood Secondary xylem Periderm Early wood Cork Epidermis Pith Cortex Primary xylem Primary phloem Transverse section of a three-year- old Tilia (linden) stem (LM) Vascular cambium Primary phloem Vascular cambium Cortex Xylem ray Epidermis Bark Primary xylem Phloem ray Growth Pith 0.5 mm 0.5 mm Xylem ray Primary xylem Secondary xylem Vascular cambium Secondary phloem Primary phloem Cork First cork cambium Periderm (mainly cork cambia and cork) Growth Primary phloem Secondary phloem Secondary xylem (two years of production) Vascular cambium Secondary xylem Vascular cambium Secondary phloem Bark Primary xylem Most recent cork cambium Layers of periderm Pith Cork