Plant Structure and Function

1. Plant Structure and Function

2. Specialized Tissues in PlantsPlant Organs: Roots, Stems, and Leaves • Roots • Anchor the plant and absorb nutrients and water • Mutualistic relationship with mycorrhizae and rhizobacteria • Transport Nutrients to the plant • Store Food

3. Specialized Tissues in Plants • Stems • Support the plant • Transport water and nutrients • Protect against predators and disease

4. Specialized Tissues in Plants • Leaves • Conduct photosynthesis • Increased SA:V with leaf size • Protect against water loss • Waxy cuticle • Stomata and Guard Cells

5. Specialized Tissues in PlantsPlant Tissues: Dermal, Vascular, and Ground Tissue

6. Specialized Tissues in Plants • Dermal Tissue • Covers the plant • Epidermis (epi = upon) – • single layer of cells on the outside of the plant • Cuticle – layer of wax that covers the epidermis and prevents water loss (polarity?) • Trichomes – tiny hairlike projections for protection • Bark – covers the epidermis in woody plants • Root hair cells are found on the epidermis of roots to help absorb water (SA:V)

7. Specialized Tissues in Plants • Vascular Tissue • Vessels that transport water and nutrients • Plant “bloodstream” • Xylem – carries water • Phloem – carries nutrients

8. Vascular Tissue - Xylem • Tracheids – hollow plant cells of the xylem with thick cell walls strengthened by lignin • Lignin resists water and is a major constituent in wood • Openings in the cell walls of tracheids allow water to pass from cell to cell and therefore be transported throughout the plant • Vessel Elements - hollow plants cells of xylem stacked end to end. • Water passes from cell to cell through slit-like openings on the ends of each cell

9. Vascular Tissue – Phloem • Sieve Tube Elements – cells of the phloem that are arranged end to end and allow nutrients to flow throughout the plant in a watery stream • Companion Cells – cells of the phloem that the sieve tube cells and aid in the movement of nutrients

10. Specialized Tissues in Plants • Ground Tissue • Produces and Stores food (sugars) • Composes most of the edible portions of plants • Contributes to the physical support of the plant • Ground tissue is composed of three main types of cells • Parenchyma • Collenchyma • Sclerenchyma

11. Ground Tissue • Parenchyma • Makes up the highest percentage of ground tissue • Thin cell walls • Large central vacuole • Limited cytoplasm • Contain many chloroplasts in leaves and are the main sight of photosynthesis

12. Ground Tissue • Collenchyma • Chains of strong, flexible cell walls • Provide support for plant organs • Sclerenchyma • Extremely thick and rigid cells walls • Found on seed coats (strong!) • Have been used to make rope from hemp

13. Plant Growth and Meristems • Meristems – regions of specialized plant cells in which mitosis produces new cells ready for differentiation • The undifferentiated cells produced are much like the stem cells of animals • Located in parts of plants that undergo rapid growth • Allow even the oldest trees to produce new leaves and new reproductive organs each year

14. Apical Meristem– located at the end (apex) of a root or stem. • Leads to increase in root or stem length • Once produced, the new cells differentiate into new dermal, vascular, and ground tissue

15. Floral Meristems • Produce the tissues of flowers • Includes the plant’s reproductive organs as well as the colorful petals that surround them