I selected links with images and information related closely to the observations described in lab Exercise 6 (Leaves) of your botany lab manual. Preview these resources as you prepare for the laboratory exercise and review these resources as you write your lab reports and study for tests.

Section I samples the Diversity and Adaptations of leaves and Section II illustrates some leaves of economic importance (leaf crops). In Section III you make external observations of leaf structure, including views of trichomes and stomates.

Give special emphasis in Exercise 6 to the prepared slides of Section IV. As you examine internal leaf anatomy (tissues and cell types). Focus your attention on identifying tissues by their location, cell types and characteristic appearance. Visualize how sections would be positioned in the intact leaf, and try to relate transverse (c.s.) with longitidinal (paradermal) sections. Learn to distinguish between (1) monocot and dicot leaves, and (2) learn to correlate leaf anatomy with environmental conditions to which leaves are adapted ( sun vs shade, air vs water, xerophytic vs hydrophytic vs mesophytic).

I. DIVERSITY AND ADAPTATIONS OF LEAVES

- I provided links to images and descriptions of the leaf types selected in the lab manual to illustrate leaf diversity and adaptations

II. LEAVES OF ECONOMIC PLANTS - LEAF CROPS

-I provided links to images and descriptions of the leaf types selected in the lab manual to illustrate leaf crops

III. EXTERNAL STRUCTURE OF LEAVES

-Although I provide links that illustrate stomates and veins in cleared leaves, these do not do justice to the fascinating views the live materials will provide as you examine the microscopic world of the leaf surface.

IV. INTERNAL LEAF STRUCTURE

-I provide links to images of Dicot leaves . Several of the cross sections are labeled and provide much detail. Also, links to paradermal sections permit you to correlate this second dimension (cut parallel to the epidermis), as the cut slowly moves from upper epidermis, past palisade mesophyll, veins, and spongy mesophyll, to the lower epidermis.

Links to the monocot, corn, provide detail of the cross section in prepared materials, and also at a lower magnification, in a slide of a fresh corn leaf section, stained with I₂KI to locate starch.

V. FREEHAND SECTIONS OF A LEAF

-In lab you will make and observe views of living leaf material that you have sectioned from leaves of the rubber tree, Ficus elastica and from corn, Zea mays. As indicated above, one link illustrates a fresh corn leaf section, stained with I₂KI to locate starch.

VI. ADAPTATIONS AND SPECIALIZATIONS OF LEAVES

- I provide links to illustrate leaves of water lily (Nymphea), an example of a hydrophyte, and leaves of (Nerium), and Pine, two examples of xerophytes. Corn, privet and lilac which were examined earlier in lab, can serve as examples of mesophytes. You may wish to check Plant adaptations for discussion of these and other plant adaptations to the environment.

VII. ABSCISSION ZONE

leaf abscission - abscission - Google images

As you review and study for a lab exam prepared to determine if a leaf is monocot or dicot, sun vs shade, right side up or up side down, etc. Also, be able to identify the following items in either a transverse or paradermal section.

1. Guard Cell
2. Palisade Mesophyll
3. Bundle Sheath
4. Vascular tissue (xylem and phloem)

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Assignment
 

                                  LEAVES
Biology 2500                                                         Botany

               Assignment for Laboratory Exercise 6 - - Leaves

1.  Examine the materials on display in the room. These will
     include leaves of living plants and preserved specimens,
     wall charts, stereo models of leaves, microscope slides,
     photographs and electron micrographs of leaves.

2.   Observe the diversity and adaptations of leaves. Record your
     notes and sketches in Table 6.1.

3.   Learn to recognize leaves of economic leaf crops. Record
     your comments and diagrams in Table 6.2.

4.   Sketch the appearance of leaf veins and trichomes as seen in
     surface view with dissecting scope (or low power of
     microscope).

5.   Sketch the appearance of open and closed stomates of
     Zebrina.

6.   Examine transverse sections of Dicot and Monocot leaves.
     Label Figures 6.1 and 6.2.

7.   Label Figure 6.3 Paradermal section of leaf.

8.  Observe freehand leaf sections of Corn and Rubber Tree.
     Label Figure 6.5.

9.  Contrast the anatomical structure of sun and shade leaves
     and leaves of xerophytes, mesophytes and hydrophytes.

10.  Prepare for a quiz next week.