Plant Structure and Function

1. Plant Structure and Function Plant Cells and Tissues

2. Plant Cells • Three basic types • Parenchyma • Collenchyma • Sclerenchyma

3. Parenchyma • Loosely packed w/large central vacuole • Cubed – shaped or elongated • Involved in • Photosynthesis • Water storage • Nutrition or healing • Bulk of nonwoody plants • Fleshy parts of fruit

4. Collenchyma • Thicker cell walls • Irregular shape • Support for plant

5. Sclerenchyma • Thick, even, rigid cell walls • Support and strengthen plant • Dead at maturity • Hardness of shells around nuts

6. Plant Tissue Systems • Dermal • Ground • Vascular

7. Dermal Tissue • Forms outside covering • Epidermis • Parenchyma cells • Cuticle • Roots develop hair – like extensions • Stomata • Woody stems/roots replaced by dead cork cells (parenchyma)

8. Ground Tissue • Surrounded by dermal tissue • All three types of plant cells • Make up majority of nonwoody plants • Main function • Storage • Metabolism • Support

9. Vascular Tissue • Surrounded by ground tissue • Made up of • Xylem • Conducts water, mineral nutrients from roots upward • Provides structural support • Phloem • Conducts organic compounds, some mineral nutrients • Alive a maturity • Adapted to different environmental conditions • Xylem support and strength • May be absent in aquatic species

10. Plant Growth • Flowering plants (Angiosperms) • Dicotyledons • Monocotyledons • Number of cotyledons or seed leaves in a plant embryo • Gymnosperms • Have two or more cotyledons

11. Monocot and Dicots

12. Plant Growth • Originates in meristems • Continuous cell division • Apical meristem (primary growth, length) • Lateral meristem (secondary growth, diameter) • Some monocots grow in length • Intercalary meristems • Located above the base of the leaves or stems (grasses) • Allows plants to regrow quickly after being grazed on

13. Lateral Meristems • Gymnosperms and most dicots • Allow stems and roots to increase in diameter • Located outside of stem

14. Lateral Meristem • Two types • Vascular cambium • Located b/w xylem and phloem • Cork cambium • Located outside phloem • Produces cork • Replaces epidermis • Provides protection and prevents water loss

15. Plants have three kinds of organs • Roots • Stems • Leaves

16. Roots • Anchor the plant in the soil • Absorb and transport water and mineral nutrients • Storage for water and organic compounds

17. Types of Roots • Taproot • Primary root • Rarely more than one – two meters • Fibrous root system • Numerous small roots • Adventitious roots • Specialized roots grow from other places • Leaves and stems • corn and epiphytic orchid (aerial roots)

19. Root Structures • Root cap • Covers apical meristem • Produces oil • Root hairs • Extensions of epidermal cells • Increase surface area • Dependent on stems and leaves for energy • Store starch

21. Primary Growth in Roots • Increase length through cell division of the apical meristem • Dermal tissue matures for form the epidermis • Ground tissue matures into • Cortex • Endodermis • Large portion of the root is made up of parenchyma cells

23. Endodermis • Inner most boundary of cortex • Semipermeable membrane (waxy layer) • Controls the flow of dissolved substances

25. Vascular tissue • Makes up innermost core of root • Dicots and gymnosperms • Xylem makes up central core • Usually forming an X • Pockets of phloem b/w lobes • Monocots • Xylem occurs in patches that circle the pith (parenchyma) • Phloem occurs b/w the xylem patches

27. Outermost layer of vascular tissues • Pericycle • Form lateral roots