1. Plant Tissues

2. Plant Tissues
Cells of a vascular plant are organized into different tissues and organs
Three major organs are: roots, stems, and leaves
Leaf
Stem
Root
Dermal tissue
Vascular tissue
Ground tissue

3. Plant Organs
Roots – absorb water and nutrients from soil, anchor plant, hold plant upright
Stems – supports plant, transports water and nutrients
Leaves – carry out photosynthesis, have adjustable pores to help conserve water, allow O2 to leave and CO2 to enter

4. Tissue Types Three tissue types: Dermal Vascular Ground Leaf Stem Root
Dermal tissue
Vascular tissue
Ground tissue

5. Dermal Tissue
Dermal Tissue – outermost layer of cells covered with a waxy cuticle to protect against water loss

6. Vascular tissue
Vascular tissue – transports water and nutrients through plant by xylem and phloem
Xylem – conducts WATER throughout the plant
Phloem – conducts NUTRIENTS throughout the plant

7. Ground Tissue
Ground Tissue – cells that lie between dermal and vascular tissues; site of photosynthesis

8. Roots
Two main types – taproots (found in dicots) and fibrous roots (found in monocots
Taproots – long primary root like that of carrots or trees
Fibrous roots – branching root system with no single root growing larger than the rest (many plants, such as grasses)

9. Root Function Anchors plant Absorbs water and nutrients
Active transport proteins in the root pump minerals and nutrients into the plant (moves from low to high concentration and requires ATP/energy to do so)
Water then moves into the roots by osmosis (high to low concentration and NO energy required) – capillary action!

10. Stems Vary greatly in size and shape Three important functions:
Produce leaves, branches, and flowers
Hold leaves up in sunlight
Transport substances between roots and leaves

11. Growth in Stems Primary growth of stems Secondary growth of stems
For the life of the plant, new cells are produced at the tips of the roots
Plant gets taller
Secondary growth of stems
Stem increases in thickness/width

12. Formation of Wood in Trees
Actually layers of xylem that build up year after year
Tree growth is seasonal
In spring, light-colored xylem cells with thin cell walls form
In fall/winter, xylem cells becomes dark and have thicker cell walls
This light and dark pattern is called tree rings. Each ring is composed of a band of light wood and dark wood

13. Formation of Wood in Trees (continued)
One ring = one year of growth
Counting rings = approximate age of tree
Thick rings = favorable conditions/good growing season
Thin rings = less favorable conditions/bad growing season

14. Layers of a Tree Trunk Wood Bark Cork Xylem: Heartwood Cork Cambium
Phloem
Vascular Cambium
Xylem: Sapwood

15. Leaves Main organ of photosynthesis
Leaves vary in shape, but all collect sunlight on flattened sections called blades
Epidermis of leaves covered by a waxy cuticle to prevent water loss

16. Leaf Functions
Photosynthesis – bulk of leaf tissue is called mesophyll, where many chloroplasts are
Gas exchange – leaves take in CO2 and give off O2 during photosynthesis

17. Leaf Functions (continued)
Leaves have stomata – pore-like openings on the underside of the leaf that allow gas exchange to occur
Stomata are open just enough to allow photosynthesis to occur, but not so much that they lose excess amounts of water
Guard cells surrounding the stomata control the opening/closing of the stomata and thus regulate the movement of gases into and out of the leaf
In general, stomata open during the day and close at night

18. Function of Guard Cells
Inner cell wall
Inner cell wall
Stoma
Stoma Open
Stoma Closed

19. Function of Guard Cells
Inner cell wall
Inner cell wall
Stoma
Stoma Open
Stoma Closed

20. The Internal Structure of a Leaf
Cuticle
Veins
Epidermis
Palisade mesophyll
Xylem
Vein
Phloem
Spongy mesophyll
Epidermis
Stoma
Guard cells