Sun Vz Shade Leaves

BI 453L Lab Exercise: Sun Leaves versus Shade Leaves

Due Date: Wednesday, November 5, 2014

Directions: See Page 9

From the course text we have the following information concerning sun versus shade leaves for many tree species:

Sun leaves

1. Are located at the top of a tree.

2. Have a smaller leaf area than shade leaves deep within the canopy.

3. Are thicker than shade leaves, with higher concentrations of rubisco, chlorophyll, and other key components of both the light reactions and carbon fixation per leaf area.

4. Sun leaves often have deeper lobing than shade leaves.

The purpose of this lab is to compare the morphology of sun versus shade leaves with respect to three criteria: weight, surface area, and thickness.

Procedure:

1. Find a tree standing in an open area. From the cortex of the tree (its outer layer of leaves) pick 10 leaves. These are your sun leaves. Be certain to collect the entire leaf and not one leaflet. Get both the blade and the petiole.

2. From the interior space of the tree canopy, pick 10 leaves. These are your shade leaves.

3. Pair a sun leaf to a shade leaf for all of your leaves. Result: 10 pairs of leaves. These pairs will be designated pairs A through J. You can use a Sharpie or magic marker to label each leaf: A1 = (sun leaf of pair A) A2 = (shade leaf of pair A) etc.

3. Weigh each member of your 10 pairs in grams, (g), measuring out two decimal places. Try to do this reasonably soon after you harvest the leaves. The leaf pairs may be kept in a plastic bag in the refrigerator for a few days. Record your values in the Table 1 below. Maintain your leaf pairs.

4. Using the calipers, measure the thickness of each leaf. Avoid the midrib. Record your answers in micrometers (μm) in Table 1. Maintain your leaf pairs.

5. Estimate leaf area by making leaf patterns Trace around the margin of each leaf blade on newsprint and cut out the paper leaf. Make a pattern for each of your sun leaves and the paired shade leaves....