Stomatal structure and physiology

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Azizah I. R. et al. (2017)

Isabella Rahma Azizah, Silvia Ayu Budiarti, Robby Ramadhani, Sukorini Ayu Alifiah, Nurul Wulandari, Yuike Dwi Yulinar, Ajeng Selvyana Pangestu,

in Departemen Biologi, Fakultas Ilmu Alam, Institut Teknologi Sepuluh NopemberSurabaya 2017 –

Stomata adalah celah atau lubang yang berada padaorgan tumbuhan yang berwarna hijau yakni daun. Stotamadibatasi oleh sel khusus yang disebut sel penjaga atau sel penutup dan dikelilingi oleh sel tetangga. Peran penting stomata yaitu sebagai pertukaran gas O2 dan CO2 sebagai hasil dari fotosintesis dan respirasi aerob, penguapan atau transpirasi, serta mencegah kehilangan air. Praktikum ini bertujuan untukmengetahui pengaruh tekanan turgor terhadap membuka danmenutupnya stomata. Praktikum ini dilakukan pengamatan terhadap membukadan menutupnya stomata pada Rhoeo discolor.  Pengamatandilakukan secara langsung menggunakan mikroskop terhadap sayatan daun Rhoeo discolor untuk mengamati stomatanya.Sayatan daun Rhoeo discolor diberi perlakuan terhadap air danlarutan gula, kemudian menghitung pengaruhnya terhadapmembuka atau menutupnya stomata dan menghitung jumlahnya. Hasil praktikum menunjukkan bahwa stomata yang diberi perlakuan dengan tetesan air lebih banyak yang terbukadaripada tertutup. Stomata yang diberi perlakuan larutan gulamenunjukkan banyak stomata yang tertutup daripada yangterbuka, karena konsentrasi larutan gula lebih tinggidibandingkan cairan intersel sehingga cairan didalam selhipotonis dan diluar sel menjadi hipertonis. Kemudian airmengakibatkan sel penjaga menjadi flacid dan menutup.

Definition, Types and Functions of Stomata



Stomata: Definition, Types and Functions (with Diagrams) | Botany

by Gupta H. (    )

Harika Gupta,

Let us learn about Stomata. After reading this article you will learn about: 1. Definition of Stomata 2. Types of Stomata 3. Top function of Stomata.

Definition of Stomata:

The stomata are minute pores which occur in the epidermis of the plants. Each stoma remains surrounded by two kidneys or bean shaped epidermal cells the guard cells. The stomata may occur on any part of a plant except the roots. The epidermal cells bordering the guard cells are called accessory cells or subsidiary cells.

Root hairs

Generally the term stoma is applied to the stomatal opening and the guard cells. The guard cells are living and contain chloroplasts in them. They also contain a larger proportion of protoplasm than other epidermal cells. Usually in the leaves of dicotyledons the stomata remain scattered whereas in the leaves of monocotyldons they are arranged in parallel rows.

Development of root hair from protruded cells

The number of stomata may also range on the surface of a single leaf from a few thousand to hundreds of thousands per square centimetre. Stomata occur on both upper and lower surfaces of leaf, but especially they are confined to the lower surface. In floating leaves Stomata are confined only on the upper surface of the leaf.

Under normal conditions the stomata remain closed in the absence of light or in night or remain open in the presence of light or in day time. Structurally the stomata may be of different types.

Types of Stomata:

The epidermis-stomata

The Epidermis

1. Ranunculaceous or Anomocytic:

Type A — (Anomocytic = irregular celled). In this type the stoma remains surrounded by a limited number of subsidiary cells which are quite alike the remaining epidermal cells. The accessory or subsidiary cells are five in number.




Guard cells of Vicia faba


2. Cruciferous or Anisocytic:


Type B – (Anisocytic = unequal celled). In this type stoma remains surrounded by three accessory or subsidiary cells of which one is distinctly smaller than the other two.

3. Rubiaceous or Paracytic:

Type C – (Paracytic = parallel celled). In this type, the stoma remains surrounded by two subsidiary or accessory cells which are parallel to the long axis of the pore and guard cells.

4. Caryophyllaceous or Diacytic:

Type D – (Diacytic = cross celled)-In this type the stoma remains surrounded by a pair of subsidiary or accessory cells and whose common wall is at right angles to the guard cells.

Stomata-types of stomata

5. Gramineous:

The gramineous stoma possesses guard cells of which the middle portions are much narrower than the ends so that the cells appear in surface view like dump-bells. They are commonly found in Gramineae and Cyperaceae of monocotyledons.

6. Coniferous Stomata:

They are sunken and appear as though suspended from the subsidiary cells arching over them. In their median parts the guard cells are elliptical in section and have narrow lumina. At their ends they have wider lumina and are triangular in section. The characteristic of these guard cells is that their walls and those of the subsidiary cells are partly lignified and partly non-lignified.

Top function of Stomata:

They are used for the exchange of gases in between the plant and atmos­phere. To facilitate this function, each stoma opens in a sub-stomatal chamber or respiratory cavity. Evaporation of water also takes place through stomata.Sunken stoma

Sensor that shows when a plant needs water

MIT engineers create sensor that shows when a plant needs water

Kristin Toussaint

in Metro, Nov. 2017

The technology can predict droughts and let farmers and gardeners know when their plants are dying, long before they wilt.

Some people have a green thumb, and others forget to water their houseplants and garden plots until all the leaves are wilting and it’s too late to save them.

But what if your plant could tell you when it needs water? That may be the future, thanks to engineers at the Massachusetts Institute of Technology.

MIT engineers have developed a sensor that can be “printed” onto a plant’s leaf and transmit data from the plant itself about if it’s experiencing water stress.

That sensor contains electronic circuit nanotechnology and is about five times thinner than a human hair, said Michael Strano, an MIT chemical engineering professor and the senior author of the new study on the development. The sensor sits on top of the plant’s “stomata,” the small pores found on leaves.

“If you look on the surface of a leaf, you’ll see millions of little pores that actually look like eyes, and they actually open and close in real time,” he said.

MIT chemical engineers have developed a sensor that detects the opening and closing of plant stomata. Gif Courtesy of Volodymyr Koman/MIT Chemical Engineering


These pores help hydrate the plant by opening to evaporate water. “You can think of it as the plant is drinking,” Strano said. “It evaporates water through the pore and that evaporation pulls water up from the soil.”

Plants start to die from lack of water days before they visibly wilt, if they even wilt at all, Strano said — and these pores show the earliest signs of drought. To develop this technology, Strano and his coauthor Volodymyr Koman stopped watering a peace lily plant and noticed a change in how those pores function.


Subsidiaries according to interstomatal space relationships

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Classification of subsidiaries according to interstomatal space relationships

by Ramayya N., Rajagopal T. (1980)

Osmania University, Hyderabad, India


in Current Science 49(11): 671-673 –

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How did plants evolve stomata ?



How did plants evolve stomata ?

by Kelly H. (2017)

Heather Kelly


A blog post by an old friend a couple of months ago (Ancient CO2 estimates worry climatologists), at this time of all times, set me thinking about how Earth has changed over time and how it is changing today in what is often described as a new, human-influenced geological epoch – the Anthropocene.  One of the biggest causes of these recent changes, (unless you believe Scott Pruitt, Donald Trump’s appointed Administrator of the Environmental Protection Agency) is increasing levels of Carbon dioxide in the atmosphere – from 2-300 parts per million in pre-industrial times to around 400 ppm today.

Terrestrial plants have tiny,  variable pores called stomata on the surface of their leaves, through which they take in the carbon dioxide they need for photosynthesis and growth and through which water is also lost (see Plants get stressed too and More thirsty plants).  The abundance of these stomatal pores on a leaf reflects the environment in which the plant finds itself; the logic goes that, when CO2 levels are high, the plant doesn’t need so many stomata to obtain enough CO2 for photosynthesis whereas, when levels drop, the density of stomata needs to increase.  Of course many other factors affect stomatal density too (light levels, availability of water, temperature and so on) but this sensitivity to CO2 levels makes stomata useful to palaeoecologists interested in working out how much CO2 may have been in the atmosphere in the distant past.  Over the years, estimates of CO2 levels based on stomatal density have been further refined by taking other factors such the shape of the stomata and carbon isotope ratios in the fossil leaves into account.

The very first plants on land evolved from green algae over 400 million years ago.  In their marine home, algae had no need of stomata to obtain the CO2they needed – CO2 can enter cells submerged in water by simple diffusion.  The simplest land plants which evolved from these algae,  mosses and liverworts, are small and are restricted to damp environments where they too, can obtain the CO2 they need by diffusion across cell walls and membranes.  Though they don’t have stomata on their leaves, mosses have stomatal-like pores on their spore capsules which are thought to help them regulate water levels as these dry out and split to disperse the mature spores inside (Pennisi, 2017).

The mystery of the evolution of stomata


The mystery of the evolution of stomata – Success of vascular plants through stomata

VIDEO:Duration: 56 mins 29 secs


The Gatsby Plant Science Summer School Lecture Collection

University of Cambridge

Prof Alistair Hetherington – Stomata: key elements essential for the success of the vascular plants. Prof Alistair Hetherington, University of Bristol, shares his research on stomata, and explains why fundamental research is important to tackling the world’s biggest problems. This research lecture was recorded at the Gatsby Summer School, 2015.