1. Tools of the Biologist/Leaf Identification

2. Tools of the Biologist Microscope *Dichotomous Key Di= two
Chotomous= fork or branch
-Good keys are region specific

3. Two ways to identify trees
Bark patterns
Leaf characteristics
What makes a tree a deciduous tree?
-broad leaf tree
-loses leaves every fall
-alternate is an evergreen tree

4. Basic Leaf Anatomy

5. Leaf Anatomy
Blade- green or colored portion of a leaf that stretches from tip to base.

6. Why do leaves turn color in fall?
In early fall, trees pull chlorophyll out of leaf and back into the stem. Requires a lot of energy to make chlorophyll, so trees conserve the energy by doing this. As a result of chlorophyll being pulled out, you then see:
Other photosynthetic pigments (carotenes and xanthopyllys)
Waste products (reds or purples)

7. Leaf Anatomy
Tip- top of blade or any place along margin where a point forms
(tips are NOT the same as teeth!)
Base- Bottom of blade
Margin- Edge of blade

8. Leaf Anatomy Main Vein- any dark, thick, easily seen vein
mid-rib- main vein that divides blade in half
“All mid-ribs are main veins, but not all main veins are mid-ribs.” ex:

9. Leaf Anatomy
Petiole- If present, stalk that connects the blade to the stem
*Some trees do NOT have petioles

10. Leaf Anatomy
7. Stipule- Bud that marks the attachment of a single leaf to the stem
-when counting leaves, count stipules NOT blades

11. Leaf Characteristics
Leaf Arrangement- How the leaves are arranged on the stem
Opposite Alternate
-stipules are -not opposite
directly across
from one another

12. Leaf Characteristics Leaf Type- Number of blades per stipule
Simple Compound
-1 blade per stipule -two or more
blades per stipule

13. Leaf Characteristics
Types of Compounding- point(s) of origin of blades
Palmate Pinnate
-All blades (leaflets) -Not palmate (two
originate from one or more points of
central point origin)
(Think: Hand)

14. Leaf Characteristics
Vein Arrangement (Venation)- How the veins appear within the blade
Palmate Pinnate
-main veins have -veins do not
a central point of originate from a
origin central point

15. Leaf Characteristics
Margin Type- How the margin appears on simple or compound leaves
Entire- smooth Toothed- 3 Types
a. finely toothed
b. coarsely toothed
c. compound toothed

16. Leaf Characteristics Lobing-
Lobe- section of the blade created by DEEP
Indentations in the margin
*Much deeper indentations than a tooth*
Palmate- maples Pinnate- oaks
**If lobed, venation and lobe type ALWAYS match.

17. Leaf Characteristics
Blade Attachment- How simple leaves are attached to the stem or how leaflets are attached to main petiole of a compound leaf
Non-sessile Sessile
- Stalked - No stalk

18. Leaf Characteristics 8. Lop-sided and Notched Blades-
Lop-sided Notched
-Blades on simple -Blades on simple
leaves (usually) that or compound leaf
lack symmetry, usually where a lack of
at the base of blade symmetry may or
may not exist

19. Leaf Characteristics
Notched and Lop-sided leaves

20. Extra Vocabulary Conspicuous- easily seen
White bloom- not a flower- cloudy white film on buds, leaves, stems,
Simple vs. compound leaflets-
Fan-shaped-
Glands- most likely dark color (black, blue, gray, brown) raised 3-D textured bump
Elongated vs. broad-