The role of stomata in the earliest land plants was to optimise carbon gain per unit water loss

The origin and evolution of stomata

Clark J. W., Harris B. J., Hetherington A. J., Hurtado-Castano N., Brench R/ A., casson S., Williams T. A., Gray J. E., Hetherington A. M. (2022)

James W Clark 1Brogan J Harris 2Alexander J Hetherington 3Natalia Hurtado-Castano 4Robert A Brench 4Stuart Casson 4Tom A Williams 2Julie E Gray 4Alistair M Hetherington 2,

  • 1 School of Biological Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK.
  • 2 School of Biological Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK.
  • 3 Institute of Molecular Plant Sciences, School of Biological Sciences, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, UK.
  • 4 Plants, Photosynthesis and Soils, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK.


Curr Biol 32(11): R539-R553 – doi: 10.1016/j.cub.2022.04.040


The acquisition of stomata is one of the key innovations that led to the colonisation of the terrestrial environment by the earliest land plants. However, our understanding of the origin, evolution and the ancestral function of stomata is incomplete. Phylogenomic analyses indicate that, firstly, stomata are ancient structures, present in the common ancestor of land plants, prior to the divergence of bryophytes and tracheophytes and, secondly, there has been reductive stomatal evolution, especially in the bryophytes (with complete loss in the liverworts). From a review of the evidence, we conclude that the capacity of stomata to open and close in response to signals such as ABA, CO2 and light (hydroactive movement) is an ancestral state, is present in all lineages and likely predates the divergence of the bryophytes and tracheophytes. We reject the hypothesis that hydroactive movement was acquired with the emergence of the gymnosperms. We also conclude that the role of stomata in the earliest land plants was to optimise carbon gain per unit water loss. There remain many other unanswered questions concerning the evolution and especially the origin of stomata. To address these questions, it will be necessary to: find more fossils representing the earliest land plants, revisit the existing early land plant fossil record in the light of novel phylogenomic hypotheses and carry out more functional studies that include both tracheophytes and bryophytes.

The Absolute Stomatal Number is constant in those leaves where differentiation of the stomata has been completed

Correlation of tissues in leaves. 2. Absolute stomata numbers

Gupta B. (1961)


Ann. Bot. 25: 71-77 –


The average number of stomata per unit area of a leaf was found to be inversely proportional to the area of the lamina. The constant obtained by the multiplication of these values is termed as the Absolute Stomatal Number. This value is constant in those leaves where differentiation of the stomata has been completed. This has been shown with shown with the developing leaves of five Solanaceous plants.

Future research using the promising model system Callitriche would open a new direction for evolutionary developmental biology studies on stomata

Figure 1. The distribution of stomata in Callitriche species. (a) Summary of the stomatal distribution and lifestyle of each species. The phylogenetic tree was constructed based on previous studies.15,19 See our recent study18 for quantitative data of the stomatal distribution. (b–i) Traced images of the adaxial and abaxial epidermis in each species; images were generated using microscopic images taken as previously described.18 Plants were grown under aerial conditions, except C. hermaphroditica, which was grown in a water-filled aquarium. Stomata are colored red and hair cells are colored black. Bars = 100 μm. (b–c) Adaxial (b) and abaxial (c) epidermis of C. japonica. (d–e) Adaxial (d) and abaxial (e) epidermis of C. palustris. (f–g) Adaxial (f) and abaxial (g) epidermis of C. terrestris. (h–i) Adaxial (h) and abaxial (i) epidermis of C. hermaphroditica.

Callitriche as a potential model system for evolutionary studies on the dorsiventral distribution of stomata

Doll Y., Koga H., Tsukaya H. (2021)

Yuki Doll, Hiroyuki Koga, Hirokazu Tsukaya,

Plant Signaling & Behavior 16: 11 –


Controlling the distribution of stomata is crucial for the adaptation of plants to new, or changing environments. While many plant species produce stomata predominantly on the abaxial leaf surface (hypostomy), some produce stomata on both surfaces (amphistomy), and the remaining few produce them only on the adaxial surface (hyperstomy).

Various selective pressures have driven the evolution of these three modes of stomatal distribution. Despite recent advances in our understanding of stomatal development and dorsiventral leaf polarity, the genetic basis for the evolution of different stomatal distributions is still unclear.

Here, we propose the genus Callitriche as a new model system to investigate patterns in the evolution of stomatal distribution. Callitriche comprises species with diverse lifestyles, including terrestrial, amphibious, and obligately aquatic plants. We found that species in this genus cover all three modes of dorsiventral stomatal distribution, making it a desirable model for comparative and evolutionary analyses on distribution modes. We further characterized the genetic basis of the different distribution modes, focusing on the stomatal key transcription factor SPEECHLESS. Future research using the promising model system Callitriche would open a new direction for evolutionary developmental biology studies on stomata.


To summarize, we characterized the stomata of Callitriche species that exhibit different stomatal distribution modes, namely amphistomy (C. terrestris), hyperstomy (C. palustris, C. stagnalis), and hypostomy (C. japonica) (Figure 1). The occurrence of all three distribution modes in the same genus will facilitate evolutionary analyses of stomatal distribution. For example, future investigations could focus on how the different lifestyles of Callitriche species have affected the evolution of stomatal distribution. Various factors including light, growth rate, leaf thickness, and herbaceous or woody nature influenced the evolution of stomatal distributions.6–8,12 However, previous studies examined few or no hyperstomatous species, many of which have amphibious or floating lifestyles. Therefore, the mechanisms by which the transition to aquatic lifestyles affected the evolution of stomatal distribution are currently unclear. The genus Callitriche could be an excellent model system to bridge this knowledge gap. Moreover, genetic pathways involved in stomata development could be investigated further. Here, we found that the spatial expression pattern of SPCH corresponds with the different stomatal distribution modes (Figure 2). Recently, the regulation and expression profiles of SPCH were investigated not only in Arabidopsis26 but also in tomato,27 another potential model for the evolution of stomatal distribution.24 A comparison of Callitriche SPCH sequences and functions with those of such other emerging model systems could provide insight into evo-devo studies of stomatal distribution. Collectively, this study illuminates the potential of the genus Callitriche as a new model system for studying the evolution of plant stomata.

Analisis tipe stomata

Analisis tipe stomata pada daun tumbuhan mlenggunakan metode stomatal printing

Fauziah A., Zahrotul ‘Izzah A. S. (2019)

Arbaul Fauziah, Annisa Salsabila Zahrotul ‘Izzah,

Tadris Biologi, Fakultas Tarbiyah dan Ilmu Keguruan, Institut Agama Islam Negeri Tulungagung


Prosiding Seminar Nasional HAYATI VII Tahun 2019 – ISBN 978-623-95106-0-2 –




Anonymous (2022)

In botany, a “stoma” (also stomate; plural stomata) is a tiny opening or pore, found mostly on the underside of a plant leaf and used for gas exchange. The pore is formed by a pair of specialized sclerenchyma cells known as guard cells which are responsible for regulating the size of the opening. Air containing carbon dioxide enters the plant through these openings where it gets used in photosynthesis and respiration. Oxygen produced by photosynthesis in the parenchyma cells (parenchyma cells with pectin) of the leaf interior exits through these same openings. Also, water vapor is released into the atmosphere through these pores in a process called transpiration.

Dicotyledons usually have more stomata on the lower epidermis than the upper epidermis. Monocotyledons, on the other hand, usually have the same number of stomata on the two epidermes.

If the plant has floating leaves, there will be no stomata on the lower epidermis and they absorb gases directly from water through the cuticle. If it is a submerged leaf, no stomata will be present on either side.

Stoma in Greek (στόμα) means “mouth”.


Definition, Types, Structure, Functions & Mechanism of Stomata

Stomata : Definition, Types, Structure, Functions & Mechanism

Swamy S. (2022)

Sagarika Swamy,

Stomata: Do you know what role nostrils play in our body? They help us in the process of breathing. Have you ever wondered do plants breathe or not? Yes, tiny pore or stomata present on the surface of leaves commence the process of breathing in plants. A stoma is a small hole in the surface of a leaf that is utilised for gas exchange in plants. The majority of the leaves have these small holes, which allow plants to take in carbon dioxide for photosynthesis and discharge waste oxygen.

There are thousands of stomata present on the surface of leaves. Most of them are found on the lower side of the leaves. We now know that plants breathe, so numerous questions, such as what stomata look like? Can plant close these pores etc., do cross our mind. In this article, we’ve provided in-detail information on stomata; their structure, types, diagram, functions, mechanism, etc. Scroll down to read more.

Structure, Types & Functions of Stomata

Stomata: Structure, Types & Functions

Grover J. (2022)

Jasmine Grover, Content Editor

Stomata are minute pores on the surface of green plants that can be easily seen under a microscope. A single pore is called the stoma, which is found in the epidermis of leaves, stems, and other organs of the plant. The stoma controls the rate of gas exchange. Stomata help in the process of transpiration and photosynthesis which are the most essential process for the survival of a plant. These processes are carried out through well-defined structures and procedures. This article discusses the definition of stomata, their structure, and their functions.

Table of Content
What are Stomata?
Structure of Stomata
Types of Stomata
Functions of Stomata
Opening and Closing of Stomata
Things to Remember
Sample Questions