Stomata in Mauseth’s book

Mauseth J. D. (2001) – Plant Anatomy – University of Texas – – (On our blog : )

Stomata in Mauseth’s book

Epidermal peel, showing ordinary epidermal cells and a stomatal complex.

Plant Anatomy 

by Mauseth J. D. (2001)

University of Texas –

Fig. 10.3-1. Epidermal peel 
of sedum (Sedum
). These preparations were made by grasping the epidermis with fine forceps, then slowly peeling the epidermis away from the leaf. In the low magnification, notice the sinuous, wavy walls of the large cells: that is a sure sign that this is from a dicot. All those cells with sinuous walls are ordinary epidermal cells. The small clusters of cells are stomatal complexes. The low magnification view shows that the stomatal complexes are located close together in this species, with only one or two ordinary epidermal cells between each complex.
            The high magnification view shows a stomatal complex. Even at this high magnification, the two guard cells are small (arrows), and the stomatal pore is closed and not visible. In addition, the stomatal complexes contain subsidiary cells (marked by S), which can be identified by their non-sinuous walls and crescent shape.
Fig. 10.3-2. Epidermal peel of cycad leaf (Cycas rumphii
). Ordinary epidermis cells in cycad leaves typically have an angular shape, often being trapezoidal. Notice that the guard cells and stomatal pores here are very large.
Stomatal density can be considered in terms of the number of stomata per square millimeter, which is a good measure of how permeable the epidermis is to the movement of carbon dioxide, oxygen and water. But density can also be considered in the number of cells that become stomatal complex cells as a percentage of all the cells in the epidermis (for example, if the number is 50% of all epidermal cells — that would indicate half of all cells differentiate into guard cells or subsidiary cells; if it is only 5%. then only 1 cell in 20 do so).
The stomatal density in terms of stomata per square millimeter is high in this species, but as a percentage of all epidermal cells, it is low.

Plant Anatomy Laboratory
Micrographs of plant cells and tissues, with explanatory text.

James D. Mauseth
Integrative Biology
University of Texas

Fig. 10.3-11. Magnification of oleander crypt. The arrows indicate three stomata present in this small portion of the crypt epidermis. In an SEM view, we would see many stomata in the bowl-shaped crypt epidermis. The numerous trichomes prevent the air inside the crypt from being disturbed by wind outside the crypt. Notice that once carbon dioxide enters the crypt and then one of the stomatal pores, it encounters a very open aerenchyma that permits it to diffuse deep into the leaf, away from the stomata. By diffusing deep into the leaf, it is more likely to enter a photosynthetic cell rather than accidentally diffusing back out of the leaf.

    This web site is being developed as supplemental material for people studying plant anatomy. Its objective is to provide light micrographs of the types of cells and tissues that students typically examine in a plant anatomy course. All micrographs are accompanied by figure legends to help the viewer interpret and understand the structures presented. Wherever possible, the microscope slides that were photographed were obtained from companies such as Triarch or Carolina Biological so that they will be similar to slides that students are examining in their college courses. This web site is designed to complement a plant anatomy course, whether that is offered through a college or through individual study at home. The descriptions here emphasize objects and concepts that might arise as a person examines samples of plant tissues, and theoretical topics are given less attention. For more comprehensive treatment of all details and theories of plant anatomy, the viewer should consult a plant anatomy text. This site is being developed by James D. Mauseth in the Section of Integrative Biology, School of Biological Sciences at The University of Texas, and the site’s organization follows his textbook Plant Anatomy.

Fig. 10.3-16. Magnification of yucca leaf. In this section of the groove, two stomata are visible (horizontal arrows); other sections often have three or four. The epidermis is not papillose for the most part, but there is a single bulging cell (vertical arrow) that partially blocks the opening of the groove (because it is a long groove, a single bulging cell will not block it completely). As with the crypts in oleander leaves, the air in this groove will be fairly calm, and if a water molecule diffuses out of one stoma here, there is a good chance it might just diffuse into the other one. Having the stomata restricted to grooves enhances water conservation.