Plant Structure

1. Plant Structure

2. Plant Tissues • A tissue is a group of cells organized to form a functional unit or a structural unit • Plants have 3 tissue systems: • Ground tissue (3 types) • Vascular tissue (xylem and phloem) • Dermal tissue (exterior)

4. Ground tissue • found throughout the plant, these tissues perform important functions: • like photosynthesis in the mesophyll tissue • Allows for storage of molecules, like glucose from photosynthesis • Provides structural support

5. Vascular Tissue • Allows for transport of food and water throughout the plant • Two Types: • Xylem - conducts water and minerals from the roots to the shoots • Phloem - conducts food from the shoots to the roots

6. Dermal Tissue • Epidermis - outermost layer, may contain a cuticle layer

7. Growth • Plant growth occurs at specialized areas called meristem

8. Specialization of Plant Tissue • Root hairs: have the ability to increase the surface area for water.

9. Cuticle layer: protects the epidermal cells for water loss

10. Guard cells: allow for the openings called stomata for gas exchange

11. Xylem and Phloem: allowing for the movement of water and nutrients to all parts of the plant.

12. Leaves • Cuticle is thicker on the top of a leaf than it is on the bottom • Stomata - opening controlled by guard cells. More stomata on bottom of leaves • Mesophyll- photosynthetic tissue of leaf • Xylem and phloem pass through mesophyll (xylem toward the top and phloem toward the bottom)

13. Mesophyll • Palisade layer - cells stacked more closely together, toward the upper epidermis, primary site of photosynthesis • Spongy layer - cells more loosely organized, toward lower epidermis, some photosynthesis, but primarily engaged in gas diffusion within the leaf

14. Leaf function • Photosynthesis - more later • Transpiration - 99% of water absorbed by plant is lost by transpiration