LEAF COLLECTIONS PROJECT

Look around your neighborhood or the park, find 10 different types of trees and take 1 GREEN leaf from the tree.  Make sure you note where that tree is so you can go back and get another leaf when the leaves change colors.

Bring the 10 leaves to class so we can look at them closely for their parts & classify them.  Monday, September 23

ACTIVITY:

LEAF KEY

LEAF KEY

LEAF KEY

LEAF KEY

LEAF KEY

TREE SCIENTIFIC NAMES

We will note the following characteristics to classify our leaves.

• SHAPE
• MARGIN (Edge of leaf)
• VENATION (Veins)
• LEAF TYPE -
• SIMPLE or COMPOUND
• SCIENTIFIC NAME of the TREE

Transportation in leaves helps water move up a plant.
Loss of water from plant leaves through transportation produces low pressure at the top of xylem tubes. This transportation pull greatly increases the ability of plants to take water to the top of a plant.

The greatest problem that leaves must overcome is water loss. 
Leaves must have openings to allow the intake of CO₂, but these same openings increase water loss in leaves. While some water must be released during transporation, leaves cannot release too much water.

Leaves are the major site for photosynthesis in most plants. These leaves have a flat blade specialized for catching sunlight. Leaves also collect carbon dioxide from the air. Leaves vary greatly from plant to plant and are useful in classification and identification. 

Leaf characteristics:

Simple and compound leaf structure:

• Simple leaves have a single blade.
• Compound leaves  have more than one blade on a single petiole. The multiple blades of a compound leaf are called leaflets.
• Palmately compound leaves have leaflets arranged like the fingers of a hand.
• Pinnately compound leaves have leaflets arranged on either side of an axis, resembling a feather.
• Trifoliolate leaves have leaflets arranged in threes, like clover.
• Compound leaves are sometimes twice divided. These leaves are called twice-compound.

Leaf arrangement: 

• Opposite - Two leaves grow opposite each other at each node.
• Alternate - One leaf grows at each node. The leaves alternate sides along the stem.
• Whorled - Several leaves grow around a single node.

 Leaf attachment: 

• Petiolate - The blade is attached to the stem by a petiole.
• Sessile - The blade is attached directly to the stem without a petiole.

Leaf shapes: 

• Linear - Narrow from base to tip.
• Elliptic - Oval-shaped.
• Ovate - Wide at the base and narrow at the tip.
• Cordate - Heart-shaped.

Leaf margins: 

• Entire - The edge of the leaf is smooth.
• Serrate - The edge of the leaf is finely toothed.
• Lobed - The edge of the leaf is deeply indented.

Leaf venation:  The system of principal veins in the leaf blade.

• Parallel - Major veins arise at the base, remain more or less parallel, and converge at the tip of the leaf.
• Net-veined or Reticulate:
• Pinnate - Major veins diverge from one large mid-vein, with smaller network connections between.
• Palmate - Several large veins arise from the base of the leaf like the fingers of a hand.
• Leaf surfaces: The presence or absence of hairs, the kinds of hairs, and the presence of other surface features, such as glands, combine to give many leaf characteristics. There are over 25 terms used to describe leaf surfaces. This amount of detail is beyond the scope of our class.