Tools of the Biologist/Leaf Identification

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

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

Basic Leaf Anatomy

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

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)

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

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:

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

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

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

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

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)

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

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

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.

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

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

Leaf Characteristics Notched and Lop-sided leaves

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-