Leaves Up Close

Leaves Up Close


 

btn1_home.gif (1256 bytes) btn1_help.gif (1225 bytes) btn1_gloss.gif (1331 bytes) btn1_outline.gif (1274 bytes)

Copyright 1999, National Gardening Association.
All Rights Reserved.

For questions regarding this web site, contact Webmaster

Leaves Up Close

 

Though leaves vary considerably, most share some basic features. Let’s look at a typical leaf up close:

Leaf Cross-Section

c1w1-bb1.gif (2032 bytes)

c1w1-bb2.gif (10942 bytes)

The upper and lower epidermis cells form a protective layer for the delicate interior cells—similar to the way your skin protects inner tissues. The upper epidermis is located on the side that normally faces the sun; the lower epidermis is on the underside of the leaf. The cuticle, (La, cutis=skin) made from a waxy substance called cutin (CUE-tin) covers the entire leaf surface to help prevent moisture loss.

Sandwiched between the epidermis cells is the mesophyll (MEZ-oh-fill; Gr. meso=middle, phyll=leaf). The mesophyll contains two layers. The upper layer consists of tightly-packed palisade cells; most photosynthesis takes place in these cells. (We’ll talk more about photosynthesis next week.) Below that is a layer of loosely-packed spongy cells that allow gases and water vapor to move about.  And woven throughout the mesophyll are the veins, or vascular tissues, responsible for transporting liquids to and from cells.

c1w1-bb3.gif (5253 bytes)

Concentrated on the lower leaf surfaces are tiny openings called stomata* (stow-MAH-tuh; Gr. stoma=mouth) that allow gases to pass in and out of the leaves. The stomata are surrounded by guard cells that collapse and swell to close and open the stomata, depending on the plant’s needs.

*plural stomata or stomates; singular stomate or stoma


btns_nav.gif (2368 bytes)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

btn_digdeep.gif (9328 bytes)

What's Stomata With You?

To give you an idea of the size of stomata, here is a list showing the number of stomata per square centimeter on the lower leaf surfaces of some different plants.

begonia          4,000
corn         6,800
sunflower       15,000
lilac       33,000
scarlet oak     103,800

Note:  One square inch = 6.25 square centimeters, so multiply these numbers by 6.25 to calculate the number of stomata per square inch.

 

Today's site banner is by Zoia and is called "Volunteer"

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.