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)

3. Ground tissue Parenchyma - found throughout the plant, these tissues perform important functions like photosynthesis Colenchyma - structural support in herbaceous plants Sclerenchyma- hard structural support (trees)

4. Parenchyma Simple tissue found throughout the plant. Functions include photosynthesis, food storage, secretion

5. Collenchyma Provides structural support Found just under the stem epidermis and along leaf veins Cells are alive at maturity and function only when they are alive

6. Sclerenchyma Hard structural support may be alive or dead and still function structurally one type of sclerenchyma is fiber (wood)

7. Xylem and Phloem Both add structural support Xylem - conducts water and minerals, long tapering cells that act as pipes of a sort Phloem - conducts food

8. Dermal Epidermis - outermost layer composed of single layer of ground parenchyma cells Periderm - many layers thick, found on woody plants, replaces epidermis, parenchyma cells

9. Growth Plant growth occurs at specialized areas called meristems (meristematic tissue) primary growth - increase in length of plant, occurs at apical meristems, secondary growth - increase in girth, occurs at lateral meristems, vascular cambium (see figure 26-16, pg 519)

10. Stems

11. Leaves

12. Arrangement on stem -pg 509 alternate opposite whorled Large surface area to collect light and allow for gas exchange but increases tendency for water loss - cuticle reduces water loss Hairs on leaves are called trichomes

13. 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)

14. 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

15. Monocots and Dicots see page 529

16. Leaf function Photosynthesis - more later Transpiration - 99% of water absorbed by plant is lost by transpiration Guttation- available water is high, transpiration is low Abscission-allows plant to shed leaves