1. Lynsey Brinker and Molly Lukacs
Stems and Leaves
Lynsey Brinker and Molly Lukacs

2. Stems
Purpose of stems
Support leaves
Store water and food
Transport water and nutrients
Growth in height only happens at roots and branches

3. Stems Special stems: Cactus Special stems: Rhizomes
Majority of cactus is a stem
Stores food and water for plant
The spines are actually leaves
Special stems: Rhizomes
Underground stem NOT A ROOT

4. Stems Special Stems: Corms Special Stems: Stolons Special stems: Bulbs
Short underground stem
Special Stems: Stolons
Slender above ground stem
Ex. Strawberry shoots
Special stems: Bulbs
Food storage ex. Onions and tulips

5. Stems Where do stems grow Apical meristems Lateral meristems
Growth occurs at tip of stem; top of the plant
Lateral meristems
Growth in diameter

6. Stems (structure) Nodes Internode Lenticels
Location where new leaves are formed
Internode
Area or space between two segments or in a joint
Lenticels
Pores in surface of the stem to allow gas exchange

7. Stems (structure) Buds Terminal Lateral Bud scales
Located at the end of a stem
Lateral
Located on side of stem
Bud scales
Protective covering around buds (embryonic shoots)

8. Stems (primary growth)
Epidermis
Outer layer of protection
Cortex
Next layer inside epidermis
Food storage

9. Stems (primary growth)
Pith
Center of stem; food storage
Vascular Bundles
Xylem
Transfers H2O
Phloem
Transfers food

10. Stems (types) Monocot Dicot Vascular bundles are scattered
Xylem in center Phloem on outside
Dicot
Vascular bundles make a circle
Xylem closer to center
Phloem behind xylem

11. Stems (secondary growth)
Occurs mostly in dicots because monocots lack lateral meristems
Stems increase in diameter due to the lateral meristems
Two types
Vascular cambium
Cork cambium

12. Stems (secondary growth)
Vascular Cambium
Produces new xylem, phloem through cell division
This becomes a secondary xylem and phloem
Wood
Secondary xylem
Heartwood (pith)
Primary xylem; stopped transporting H2O

13. Stems (secondary growth)
Sapwood
New secondary xylem
Lighter colored
Bark
Provides protection for woody stems
Made up of cork. cork cambium, phloem

14. Stems Why is bark rough or cracked Cells aren’t living
Cork cambium produces cork and dies before maturity
As the tree grows cork ruptures and cracks

15. Stems
How old is my tree?
Annual rings show the growth of the tree per season
They can be used to tell the approx. age of tree
Thick rings = moist good growing conditions
Think rings = drought or poor growing season

16. Leaves (function) Primary site of photosynthesis Leaf structures
Site of transpiration
Site of gas exchange
Leaf structures
Important for plant id
Blade: broad, flat portion: site of photosynthesis
Petiole: stalk like region where it attaches to stem

17. Leaves (three tissue layers)
First
Epidermis layer: usually one cell layer thick
On top and bottom of leaf
Impermeable cuticle (top and bottom)
H2O, O2, and CO2 enter and exit through stomata (bottom only)

18. Leaves (three tissue layers)
Second
Mesophyll layer – organized into two layers
Palisade Mesophyll
Lays directly beneath upper epidermis
Tightly packed into one or two cell layers
Spongy Mesophyll
Beneath palisade layer
Balloon shaped cells

19. Leaves (three tissue layers)
Vascular layer
Consists of vascular bundles called veins (circular)
Continuous with vascular bundles in stem and petiole
Veins branch repeatedly so each cell in less than 1mm from a vein

20. Leaves (venation) Arrangement of veins in a leaf Monocots vs Dicots
Parallel venation ex. Grasses
Dicots
Net venation ex. maple

21. Leaves (processes) Transpiration Gas Exchange
Evaporation of water in plants through stomata
Gas Exchange
Exchange of CO2 and O2 through stomata
Stomata: bordered by 2 kidney shaped guard cells
Modified epidermis cells that regulate H2O and gas exchange
Open during day closed during night: contained chloroplasts

22. Leaves (processes) Photosynthesis
Process when chlorophyll and enzymes in leaves convert certain wave lengths of light to chem. energy
Equation Sunlight + CO2 + H2O > Carbohydrates + O2

23. Leaves (photosynthesis)
Chloroplasts: Sacks that contain photosynthetic pigments
Site of photosynthesis
Thylakoids: Series of flattened sacks
Acts like solar panels to collect sun energy
Grana: Stacks of thylakoids
Stroma: Liquid solution which contains 4 pigments
Surrounds grana

24. Leaves (photosynthesis)
Chlorophyll
Chlorophyll A = 95%
Chlorophyll B = 5%
2 other pigments
Xanthophylls – yellows
Carotenes – oranges

25. Leaves (photosynthesis)
Spring/Summer
Only green is reflected = seen
All other colors hidden
Fall colors
Chlorophyll is all used up, see all other reflected pigments
Chromatography
Technique used to separate a mixture into its different components

26. Leaves (plant id) 1. Arrangement of leaves on stems
2. Divisions in a leaf
3. Shape
4. Character of leaf margin
5. Veins

27. Interactive Links Leaf Game Why Leaves Change Colors All About Leaves
Why Leaves Change Colors
All About Leaves
Stems, Leaves, and Transpiration
Stem Activity

28. Videos Plant nutrition and transport Parts of a plant – stems
Parts of a plant – stems
The parts of a plant and its function
Why leaves change color
Leaf color chromatography

29. Work Cited Dictionary.com. Dictionary.com, n.d. Web. 08 Jan. 2015.
"Leaves and Leaf Anatomy - EnchantedLearning.com." Leaves and Leaf Anatomy - EnchantedLearning.com. N.p., n.d. Web. 06 Jan
"Plant Biology: Roots, Shoots, Stems, and Leaves." - For Dummies. N.p., n.d. Web. 08 Jan
"Plant Stem." Wikipedia. Wikimedia Foundation, n.d. Web. 08 Jan

30. Work Cited
"Plant Structure and Function." Plant Structure and Function. N.p., n.d. Web. 05 Jan
"Plant Structures: Cells, Tissues, and Structures." Plant Structures: Cells, Tissues and Structures. N.p., n.d. Web. 06 Jan
"Plant Structures: Leaves." Plant Structures: Leaves. N.p., n.d. Web. 06 Jan
Richards. "Plants: Roots, Stems, and Leaves." Plants: Roots, Stems and Leaves (n.d.): n. pag. Web. 06 Jan