Difference Between Stomata of Monocot and Dicot Plants

Main Difference – Stomata of Monocot vs Dicot Plants

Monocot and dicot plants contain stomata in their leaves as well as in their stem. The major role of stomata is to facilitate the gas exchange. They also facilitate transpiration, which helps the absorption of water from the soil and the transport of water through the xylem. The size of the stomata is controlled by a pair of guard cells. The main difference between stomata of monocot and dicot plants is that the guard cells of the monocots are dumbbell-shaped whereas the guard cells of dicot plants are bean-shaped.

Key Areas Covered

1. Stomata of Monocot Plants
      – Definition, Guard cells, Distribution of Stomata
2. Stomata of Dicot Plants
      – Definition, Guard cells, Distribution of Stomata
3. What are the Similarities Between Stomata of Monocot and Dicot Plants
      – Outline of Common Features
4. What is the Difference Between Stomata of Monocot and Dicot Plants
      – Comparison of Key Differences

Key Terms: Amphistomatic, Bean-Shaped Stomata, Dumbbell-Shaped Stomata, Guard Cells, Hypostomatic, Lower Epidermis, Stomata of dicot Plants, Stomata of Monocot Plants, Transpiration, Upper Epidermis

Stomata of Monocot Plants

Stomata of monocot plants are the tiny pores in the upper and the lower epidermis of monocot leaves, which are surrounded by a pair of dumbbell-shaped guard cells. Since the stomata of monocots are equally distributed in both upper and the lower epidermis, the stomata distribution of monocots is known as an amphistomatic distribution. The dumbbell-shaped stomata of a maize plant are shown in figure 1.

Difference Between Stomata of Monocot and Dicot Plants

Figure 1: Maize Stomata

Due to the amphistomatic distribution of stomata in monocots, the frequency of transpiration can be high than that of a dicot leaf. Therefore in the presence of excess sunlight, monocot leaves are rolled to reduce the surface area of the leaf, preventing the water loss. Ideally, gymnosperms contain sunken stomata, which are deeply embedded in the leaves as an adaptation to prevent excess transpiration.

Stomata of Dicot Plants

Stomata of dicot plants are tiny pores in the lower epidermis of dicot leaves, which are surrounded by a pair of bean-shaped guards cells. Since the stomata of dicot plants only occur on the lower surface of the leaf, the distribution of stomata of dicot plants is known as a hypostomatic distribution. The bean-shaped stomata of dicots are shown in figure 2.

Main Difference - Stomata of Monocot vs Dicot Plants

Figure 2: Dicot Stomata

The hypostomatic distribution of dicot stomata helps to prevent the water loss by transpiration. However, some dicot plants contain a considerable amount of stomata in the upper epidermis as well. But, these plants show adaptations such as trichomes to reduce the water loss from the upper epidermis. The plants that grow on the water surfaces contain their stomata in the upper epidermis. Xerophytic plants, which grow in deserts, also contain sunken stomata.

Similarities Between Stomata of Monocot and Dicot Plants

Most of the stomata of monocot and dicot plants occur in the plant leaves.
The major role of the stomata of monocot and dicot plants is to facilitate the gas exchange.
Both stomata of monocot and dicot plants are surrounded by a pair of guard cells.
Some monocots and dicots contain sunken stomata.

Definition

Stomata of Monocot Plants: Stomata of monocot plants are tiny pores in the upper and lower epidermis of monocot leaves, which are surrounded by a pair of dumbbell-shaped guards cells.

Stomata of Dicot Plants: Stomata of dicot plants are tiny pores in the lower epidermis of dicot leaves, which are surrounded by a pair of bean-shaped guards cells.

Guard Cells

Stomata of Monocot Plants: The stomata of monocot plants are surrounded by dumbbell-shaped guard cells.

Stomata of Dicot Plants: The stomata of dicot plants are surrounded by bean-shaped guard cells.

Arrangement

Stomata of Monocot Plants: The stomata of monocot plants are arranged in regular arrays.

Stomata of Dicot Plants: The stomata of dicot plants are arranged in an irregular pattern.

Upper/Lower Epidermis

Stomata of Monocot Plants: Monocots plants contain stomata in both upper and lower epidermis.

Stomata of Dicot Plants: Dicot plants contain most stomata in the lower epidermis.

Prevention of Water Loss

Stomata of Monocot Plants: The leaves of the monocots are rolled to reduce the exposed surface area to the sunlight.

Stomata of Dicot Plants: The distribution of stomata in the lower epidermis of dicots reduces the water loss by transpiration.

Conclusion

Stomata of monocot and dicot plants are kind of pores that occur in leaves and stem, facilitating the gas exchange. Transpiration also occurs through stomata. Monocots contain dumbbell-shaped guard cells, surrounding their stomata. In contrast, dicots contain bean-shaped stomata, surrounding the stomata. Monocots contain stomata in both upper and the lower epidermis of leaves. But, most dicot stomata of dicots occur in the lower epidermis. The main difference between stomata of monocots and dicots is the anatomy of the guard cells and distribution in the epidermis of the leaves.

Reference:

1. “Stomata: Structure, Number, Distribution and Type of Stomata | Transpiration.” Biology Discussion, 26 Oct. 2015, Available here.

Image Courtesy:

1. “Maize stomata” by Umberto Salvagnin (CC BY 2.0) via Flickr
2. “Stomata” by AJC1 (CC BY-SA 2.0) via Flickr