The types are: 1. Anomocytic 2. Anisocytic 3. Paracytic 4.
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The types are: 1. Anomocytic 2. Anisocytic 3. Paracytic 4. Diacytic 5. Actinocytic 6. Gramineous 7. Hemiparacytic 8. Type 1. Anomocytic also called ranunculaceous or irregular-celled type : Anomocytic stoma remains surrounded by cells that are not different from other epidermal cells so far as size and shape are concerned. There exist no definite number and arrangement of cells that surround a stoma.
A stoma appears to be embedded in epidermal cells. Apocynaceae, Boraginaceae, Chenopodiaceae, Cucurbita etc. Metcalfe and Chalk mentioned families where anomocytic stoma is present. Type 2. Anisocytic also called Cruciferous or unequal-celled type : Anisocytic stoma remains surrounded by three unequally sized subsidiary cells, among which one is distinctly smaller in size than the other two.
Cruciferae, Solanum, Petunia, Sedum and Nicotiana etc. Metcalfe and Chalk mentioned 37 families where anisocytic stoma occurs. Type 3. The longitudinal axes of subsidiary cells lie parallel to that of aperture and guard cells. The subsidiary cells may or may not meet over the poles. In the family Rubiaceae the subsidiary cells usually meet over the poles.
The subsidiary cells of Drvnys and Linum etc. Rubiaceae, Convolvulaceae, Phaseolus, Arachis and Psoralea etc. Metcalfe and Chalk cited families where paracytic stoma is found.
Type 4. Diacytic also called caryophyllaceous or cross-walled type : Diacytic stoma remains surrounded by a pair of subsidiary cells. The common wall of the subsidiary cells is at right angles to guard cells.
Caryophyllaceae, Acanthaceae, Hygrophila, Dianthus etc. Metcalfe and Chalk mentioned eleven families to have diacytic stoma. Type 5. Actinocytic: Actinocytic stoma remains surrounded by a circle of radiating cells. Ancistrocladus and Euclea pseudebenus Ebenaceae. It is to note that Metcalfe and Chalk in the original definition of actinocytic did not state the number of subsidiary cells that enclose a stoma. Type 6. Gramineous: Gramineous stoma possesses two guard cells that are shaped like dumb-bells.
Each guard cell has a narrow middle portion and two bulbous ends. The narrow middle portion is strongly thickened. The subsidiary cells occur parallel to the long axis of pore. Gramineae and Cyperaceae. They thought that more terms would be necessary and so added another term —actinocytic. The terms ranunculaceous, cruciferous, rubiaceous and labiatous or caryophyllaceous stoma were coined by Vesque in Later studies revealed that these types are not confined to respective families only.
Identical types occur in very distantly related families. Therefore Metcalfe and Chalk proposed new terms respectively anomocytic, anisocytic, paracytic and diacytic instead of ranunculaceous, cruciferous, rubiaceous and labiatous or caryophyllaceous. In addition to gramineous stoma Metcalfe described a new stomatal type in monocotyledons. It is termed tetracytic where the guard cells are surrounded by four subsidiary cells —two laterals and two polar, each being present on the four sides.
The two laterals lie parallel to guard cell. The two polar subsidiary cells are often smaller. Tetracytic stoma characterizes numerous monocotyledonous families. It is also reported from dicotyledons, e. Tilia and some members of Asclepiadaceae.
The seven types of stoma five from dicotyledons and two from monocotyledons according to Metcalfe and Chalk and Metcalfe are shown in Fig. Diagrammatic representation of different types of stoma in dicotyledons and monocotyledons. Guard cells are hatched. In addition to the above five types of stoma in dicotyledons Van Cotthem illustrated two more types of stoma, which are as follows Fig. Hemiparacytic: The stoma is accompanied by a single subsidiary cell, which is placed parallel to the long axis of the pore and this cell may be long or short in length in contrast to the guard cells.
Example: Glinus latioides and Trianthema lancastrum etc. Type 8. The size of subsidiary cells may be of two different types: a The two polar cells may be as broad as the stomatal complex e. Stace illustrated the cyclocytic Fig. The stoma is surrounded by four or more subsidiary cells, which form one or two narrow rings around the guard cells. The basis of classification is the presence or absence of subsidiary cells and when present the number, shape and arrangement in relation to guard cells form the basis.
Stebbins and Khush did not propose any terminology to aid their concepts and distinguished them as First type, Second type, Third type and Fourth type which are as follows Fig.
In Rhoeo, Tradescantia and Zebrina of Commelinaceae there are four subsidiary cells. Each subsidiary cell occurs on each of the four sides of paired guard cells. As a result the stomatal complex has square appearance in surface view. The additional subsidiary cells occur on the lateral sides of stoma, each being present on each of the two lateral sides.
In contrast to Zebrina, Commelina has four subsidiary cells on lateral sides, two being present on each of the two lateral sides of paired guard cells. Second type: The two reniform guard cells of stoma remain surrounded by subsidiary cells that are in number. Two subsidiary cells are smaller and roundish than the rest. The roundish cells are present at the ends of paired guard cells —each being present on each end. In Pandanus haerbachii Pandanaceae there are four subsidiary cells among which two are smaller and roundish than the other two.
The roundish cells occur at the ends and other two elongated subsidiary cells are present on the lateral sides of the paired guard cells. In Phytelephas microcarpa there are well defined six subsidiary cells. The roundish cells are situated at the ends of paired guard cells, each being on each end.
The rest occurs on lateral sides, two being on each side. Such type of stomatal complex with four subsidiary cells occurs in Calycanthaceae.
Third type: The two guard cells of stoma remain surrounded by two subsidiary cells each being present on each lateral side of guard cells. This is the most common and predominant type of stomatal complex and spreads over 24 monocot families so far investigated. Ex Juncales, Graminales, Cyperales, Typhales etc.
Fourth type: The two guard cells of a stoma are without any subsidiary cells. A stoma appears to be embedded in the epidermal cells. Amaryllidales, Iridales, Orchidales etc. Paliwal distinguished morphologically five main types of stoma in monocotyledons Fig. The stomatal complexes are as follows: 1.
Members of Liliaceae, Orchidaceae etc. Cyperaceae, Palmae etc. Members of Zingiberaceae and b Each of the four subsidiary cells is situated on the four sides of guard cells, i. Members of Commelinaceae, Palmae, Musaceae etc. Agavaceae, Araceae etc. Related Articles:.
Top 8 Types of Stoma in the Epidermis | Plants
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.
Types of Stomata in Plants Stomata are minute pores which occur on epidermal surface of leaves and also some herbaceous stems. Each stoma is guarded by two specialised epidermal cells, called guard cells. These guard cells are also surrounded by other specialised epidermal cells called subsidiary cells or accessory cells. These cells also plays an important role during opening and closing of stomata. Metcalfe and Chalk classified stomata on the basis of number and arrangement of the subsidiary cells in to the following types: 1. Anomocytic irregular celled or Ranunculaceous: In this type, the stomata remains surrounded by limited number of subsidiary cells which are quite alike the remaining epidermal cells. Example: Ranunculaceae, Malvaceae, Papaveraceae 2.