The lower epidermis contains most of the stomata. Each stoma is surrounded by guard cells that regulate the opening and closing of the stomata and control the exchange of gases between the leaf and the surrounding atmosphere.

Guard cell
Guard cell Biology-Online.org Guard cells are plant cells, but what is their function? Visit the website to learn what they do.
http://www.biology-online.org/dictionary/Guard_cel...
Leaf guard cells - Flickr
Leaf guard cells By Antoine Hnain This is a crossection of a leaf which reveals the stomata (with two guard cells) which control the transfer of gases and moisture moving in and out of the leaf.
http://www.flickr.com/photos/tonios-pics/387510814...
Stoma
Stoma Wikipedia.org In botany, a stoma (also stomate; plural stomata) is a pore, found in the leaf and stem epidermis that is used for gas exchange. Visit the web page for illustrations and t
http://en.wikipedia.org/wiki/Stoma
Structure And Working Of Stomata
Structure And Working Of Stomata TutorVista Video YouTube.com Video length: 03:51.
http://www.youtube.com/watch...
Video for Plant Stomata
Video for Plant Stomata sachinjoshi87 | June 16, 2007 YouTube.com Video length: 01:07.
http://www.youtube.com/watch...
Why does the lower epidermis have more stomata than the upper epidermis of a leaf?
Why does the lower epidermis have more stomata than the upper epidermis of a leaf? Yahoo Answers Does it have something to do with transpiration? Visit the web site to find out.
Why does the lower epidermis have more stomata than the upper epidermis of a lea...