1. LEAVES

2. Coniferous VS Deciduous

3. Which is Which?

4. Characteristics of Conifers
Needle shaped leaves
Seeds that develop inside cones
Evergreen – green year round
Gymnosperm, conifer, softwood
Examples: pine, spruce, hemlock, fir

5. Examples of conifers Balsam fir Red pine Douglas fir White pine
Fraser fir
Scotch pine

6. Conifer leaves
Scale like
Needle like

7. Conifer needles
Clusters
Singles

8. Deciduous Tree Characteristics
Broad flat leaves
Lose all leaves each year in the fall
Angiosperm (flowering plants), broadleaf, hardwood
Examples: oak, maple, beech, aspen, ash

9. Deciduous examples Red oak Elm Honey locust Red maple White birch
beech
Crimson king
Black locust

10. Exceptions
Larch trees have cones and needles, but lose their leaves each year.
Yew trees have needle shaped leaves and are evergreen but have berries not cones.
Holly trees have broad flat leaves and it is evergreen.

11. Leaf Characteristics/ID

12. Leaf Characteristics-Deciduous
Leaf arrangement: whorl, alternate, opposite
Leaf type: simple or compound
Leaf margin: entire, lobed, toothed– others exist
Leaf texture: hairy, waxy, rough, smooth, thick, thin, etc.
Leaf shape: ovate, obovate, lanceolate, cordate, elliptical, etc. – others exist

13. 1.

14. What is the leaf arrangement?

15. What is the leaf arrangement?

16. 2. Leaf Type

17. Simple Compound Only one leaf blade
Joined by its stalk to the woody stem
Examples: maple, oak, aspen, beech
Made up of several leaflets
Leaflets are joined to a midrib that is not woody
Examples: ash, walnut, sumac

18. Simple or Compound?

19. What is the leaf type?

20. 3. Leaf Margins 1. Entire = margin lacks teeth (smooth)
2. Serrate = saw-tooth with the teeth pointing forward
3. Lobe = projecting part or segment of the leaf
- Space between two lobes is a sinus
- Example maple or oak

22. 4. Leaf Texture
hairy, waxy, rough, smooth, thick, thin, etc. Describe the “leaf” of the aloe plant

23. 5. Leaf Shapes Ovate = egg-like shape, broadest part below the middle
Obovate = shaped like an egg, broadest part above the middle
Lanceolate = much longer than wide
Cordate = shaped like a heart
Elliptical = have an ellipse shape, broadest part in the middle

25. External Leaf Structure

26. External Leaf Structure
Tip
Margin
Vein
Blade
Spine
Midrib
Base
Petiole

27. External Leaf Parts
1. The large broad part of a leaf is the leaf blade
Large surface area for photosynthesis
Supported by a system of veins that contain xylem and phloem
2. Main vein running down the middle is the midrib
Help position the blade in a way that it is facing a light source

28. External Leaf Parts
3. The leaf blade is connected to the stem by the petiole
Lifeline between the leaf and the rest of the plant
Water and minerals flow into the leaf blade and food flows out of the leaf blade through the petiole
4. The edge of the leaf blade is referred to as the margin
Wavy, toothed, lobed, and entire or smooth.

29. External Leaf Parts
5. On top of the leaf is a waxy non-cellular layer called the cuticle
Prevents water from escaping
Plants in bright arid conditions have thick cuticles to retain water
6. Veins
Contain xylem and phloem (stem cells that allow for movement of nutrients/waste)

31. Internal Leaf Structure

32. Internal Leaf Parts
1. The epidermis is the skin-like layer of cells on the top AND the bottom surface of the leaf
The epidermis may be one or many layers thick
Protective
2. Between the epidermal layers is the mesophyll
Photosynthetic occurs in mesophyll cells
Network of veins containing xylem and phloem tissues
2 Types:
Palisade mesophyll – tightly packed cells standing on end directly beneath upper epidermis
Spongy mesophyll – loosely packed cells, form air spaces to hold products of photosynthesis, under palisade

33. What are the functions of the internal components of a leaf?
Leaves have openings in the epidermis called stomata
singular: stoma
Allow the diffusion of carbon dioxide, oxygen, and water.
Specialized cells called guard cells control the opening and closing of the stomata

34. 4. Trichomes
- Specialized cells that appear as hairs on the leaves of some plants
Reduce water loss by slowing air movement
Discourage some pests from devouring the leaves
Example: soybeans

37. Cuticle
Epidermis
Palisade
Chloroplast
Vein
Xylem
Spongy
Layer
Phloem
Air Space
Guard Cell
Epidermis
Stoma
Cuticle

38. Additional Comments – Internal Structure
Chloroplast
Organism containing chlorophyll which is green and collects light energy
Xylem
Transports water and nutrients up the plant
Phloem
Transports sugars down the plant
Guard Cell
Controls moisture and gas exchange
Open when plant is well watered and closed when the plant is dry