Presentation is loading. Please wait.

Presentation is loading. Please wait.

Stems and Leaves Lynsey Brinker and Molly Lukacs.

Similar presentations


Presentation on theme: "Stems and Leaves Lynsey Brinker and Molly Lukacs."— Presentation transcript:

1 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 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 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 Growth occurs at tip of stem; top of the plant Lateral meristems Growth in diameter

6 Stems (structure) Nodes 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 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 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 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 Monocots Parallel venation ex. Grasses Dicots Net venation ex. maple

21 Leaves (processes) Transpiration 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 Stems, Leaves, and Transpiration Stem Activity

28 Videos Plant nutrition and transport https://www.youtube.com/watch?v=bsY8j8f54I0 Parts of a plant – stems https://www.youtube.com/watch?v=VuMxN1j9f6Y The parts of a plant and its function https://www.youtube.com/watch?v=CPAIr1sY9RU Why leaves change color https://www.youtube.com/watch?v=cyj7kyYX_gQ Leaf color chromatography https://www.youtube.com/watch?v=qH-AJDqsSII

29 Work Cited Dictionary.com. Dictionary.com, n.d. Web. 08 Jan "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


Download ppt "Stems and Leaves Lynsey Brinker and Molly Lukacs."

Similar presentations


Ads by Google