CLASSIFICATION OF STOMATAL TYPES. The dicotyledons stomata were firstly classified into 4. types by Yesque in the year The names for your types

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1 28 CLASSIFICATION OF STOMATAL TYPES A. MORPHOLOGICAL OR TOPOGRAPHICAL CLASSIFICATION: The dicotyledons stomata were firstly classified into 4 types by Yesque in the year The names for your types were given after the family in which these types were first studied. The four types as defined by Yesque (1889) are as follows: (i) Ranunculaceous type: Stoma mother cell is cut off by a simple U-shaped wall; mature stomata are surrounded by several irregularly disposed epidermal cells. (ii) Cruciferous type: The stoma mother cell is cut off in the primordial cell by three or more cell walls inclined to one another at an angle of about 60 ; mature stomata are surrounded by three subsidiary cells, of which one is, smaller than the other two. (iii) Caryophyllaceous or Labiateous type: Stoma mother cell is cut off into the primordial cell by two U-shaped cell walls oriented in opposite directions, the second being attached to the concavity of the first, mature stomata are suspended in the middle of an epidermal cell by two cell walls perpendicular to the pore. (iv) Rubiaceous type: Stoma mother cell is cut off in the primordial cell by two parallel walls; mature stomata are accompanied by two subsidiary cells parallel to the long

2 29 axis of the pore. In order to remove the impression that the particular type of stomata are not restricted to certain families only; Metcalfe and Chalk (1950) replaced these terms by more general descriptive ones: "anomocytic for Mranunculaceous, "anisocytic for "Cruciferous ; "diacytic for "Caryophyllaceous or "labiateous and "paracytic for "rubiaceous. Since Metcalfe and Chalk (1950) proposed these terms; they have been in use in most research papers to indicate the structure and position of the epidermal or subsidiary cells. The different terms of Metcalfe and Chalk (1950) are defined as under: (i) Anomocytic (irregular-celled)type: The stoma is surrounded by a definite number of cells that are not different from the remainder of the epidermis. / (ii) Anisoeytic (unequal celled) type: The stoma is surrounded by three cells of which one is distinctly smaller than the other two. (iii) Diacytic (Cross-celled) type: The stoma is enclosed by a pair of subsidiary cells whose common wall is at right angles to the guard cells. (iv) Paracytic (parallel celled) type: The stoma is accompanied on either side by one or more subsidiary cells parallel to

3 30 the long axis of the pore and guard cells. The following morphological terms have been added to this list: (v) Actinoc.ytic type: The stoma is surrounded by a circle of radiating cells (Metcalfe and Chalk, 1950). (vi) Cyclocytic type: The stoma is surrounded by 4 or more cells forming a narrow ring around the guard cells (Stace, 19650* (vii) Tetracytic type: The stoma is surrounded by four subsidiary cells, 2 lateral and 2 polar, the polar sometimes smaller and roundish (Metcalfe,1961). (viii) Stoma with a single subsidiary cell; : The stoma is accompanied by a single subsidiary cell either shorter or longer than the guard cells and which mostly lie parallel to the long axis of the pore. Van Cotthem (1970) designated this as a hemiparacytic. B. MORPHOGENETIC OR ONTOGENETIC CLASSIFICATION: The stoma mother cell or stomatal initial called the meristemoid is cut off from a cell of the protoderm. The stomatal initial undergoes one or more divisions to give rise to a stoma. A stomatal meristemoid which divides to form two equal guard cells is called a guard mother cell. I. Prantl^ classification (1872); It was Prantl (1872) who firstly recognised two main ontogenetic types of stomata as under

4 31 (i) Direct type: The stoma initial undergoes only two divisions, cutting off a mesogene neighbouring cell during the first division before the second segment form the two guard cells during the second division. (ii) Indirect type; The stomata initial divides three or more times to give rise to two or more mesogene neighbouring and encircling cells before forming the guard cells. II. Florin's classification ( ): The gymnosperm stomata were classified into two following ontogenetic types by Florin (1931, 1933): (i) Haplocheilic type: A stoma mother cell directly dunctions as a guard mother cell which divides to produce a pair of guard cells only without cutting off any subsidiary cells.. (ii) Syndetocheilic type: A stomatal initial functions as a guard mother cell after cutting off one or more subsidiary cells. Florin (1931, 1933) did most of his work on fossil material and, therefore, his conclusions many times were based upon the structure of mature stomata. After the publication of Florin's (1931, 1933)work, many research workers used these ontogenetic terms for the description of mature stomata too on the basis of presence or absence of subsidiary cells. Then, later on it was proved that neither the presence of many subsidiary cells did not always necessarily involved a syndetocheilic ontogeny; nor did the absence of subsidiary cells involved always a haplocheili

5 32 ontogeny. Florin (1933), therefore, proposed to replace the terms "mesogenous" for syndetocheilic and "perigenous" for haplocheilic to indicate that the epidermal cells around the stoma (neighbouring or subsidiary cells) develop or not from the same stomatal initial as the guard cells. (iii) Mesoperigenous: This term is coined by Pant (1965) to this ontogenetic classification of the stomatal types to denote that the surrounding cells are of dual orogin, at first typically one mesogene neighbouring cell and guard mother cell are formed from the meristemoid, while the remaining perigene are those which happen to lie on the other side of the meristemoid. III. Pant s classification (1965): Pant (1965) divided these three maintypes mesogenous, mesoperigenous and perigenous into ten subtypes as follows: 1. Mesogenous are further subdivided depending upon the number of cutting faces of the meristemoid which corresponds to the number of subsidiary cells: (i) Unilabrate (ii) Dolabrate (a) Mesoparacytic (b) Mesodiacytic (c) Pyrrosia type (iii) (iv) Trilabrate Tetralabrate

6 33 2. Mesoperigenous subdivided on the basis of plane of division of the guard mother cell: (i) Plagiogyria type (at right angles) (ii) Tetracentron type (parallel) (iii) Ranunculus type (at any angle) 3. Perigenous type. IV. Maroti*s classification (1966): Maroti (1966) used thjfcfie two ontogenetic terms,viz.: (i) Haplochell (ii) Syndetocheil V. Paliwal's classification (1969): Paliwal (1969) classified the monocot stomata into following five categories depending upon the number of perigenes: (i) Asahkoshik (Aperigenous) (ii) Dwisahkoshik (Biperigenous) (iii) Chatusahkoshik (Tetraperigenous) (iv) Shatsahkoshik (Hexaperigenous) (v) Bahusahkoshik (Multiperigenous) (VI) Payne's classification (1970): Payne (1970) recognised two new following mesogenous stomatal patterns in the dicotyledons (i) Helicocytic: Stoma is surrounded by a helix of four or more mesogene subsidiary cells. (ii) Allelocytic: Stoma is surrounded by an alternating comple of three or more C-shaped mesogene subsidiary cells of graded sizes. Allelocytic stoma is known as: (a) Paralleloc.vtic when the guard cells are developed

7 34 parallel to the subsidiary cells and (b) Mall elocy tic when the guard cells are developed at right angles to the subsidiary cells. (VII) Frvns-Claessens and Van Cotthea^s classification (1973): Fryns-Claessens and Van Cotthem (1973) classified the stomata of vascular plants into following 26 ontogenetic categories: A. Perigenous stomata: Type: 1. aperigenous 2. monoperigenous 3* diperigenous 4. tetraperigenous 5. hexaperigenous 6. polyperigenous (Cycloperigenous) B. Mesoperigenous stomata: Type: 7. anomo-mesoperigenous 8. dia-mesoperigenous 9. hemipara-mesoperigenous 10. eupolo-mesoperigenous 11. copolo-mesoperigenous 12. anisoperigenous 13. stauro-mesoperigenous 14. para-mesoperigenous 15. cyclo-mesoperigenous

8 35 C. Mesogenous stomata: Type: 16. desmo-mesogenous 17. Euperi-mesogenous 18. Coperi-mesogenous 19. Duploperi-mesogenous 20. Dia-mesogenous 21. Para-mesogenous 22. Cyclo-mesogenous \ V allelo-mesogenous 24. aniso-mesogenous 25. helieo-mesogenous 26. Tetra-mesogenous DISPERSION7OF STOMATA On the lamina, the stomata are more or less uniformely dispersed over the whole surface in between the veins, sometimes over the finer veins but mostly not over the main veins. The stomata are very rarely present over the major veins. In other words, the dispersion of the stomata is homogeneous in most plants. This may not be always true, as stomata are sometimes more numerous on certain parts of leaves and competely absent from other pats. Sometimes, stomata are dispersed in distinct groups. The dispersion of stomata is more or less homogeneous in other foliar organs like lamina, such as stipule, bract, bractiole, calyx, corolla etc. Usually, the stomata are separated from one another by one or more epidermal cells, but sometimes two or more stomata occur grouped together in close contact with

9 36 each other; such stomata in literature are called contiguous. The stomata are either sunken or situated in grooves or grouped together and often covered by thick layer of hairs in xerophytes. The stomata present in intercoastal zones and form longitudinal rows. Ecological factors such as humidity, wind, temperature and position of the leaf on the plant etc. also influence the number of stomata. ORIENTATION OF STOMATA: In foliar organs such as lamina, stipule, bract,^corolla etc, the orientation of stomata may be irregular, while in the cylindrical organs like stem, petiole, peduncle, style, filament of the stamen etc, the orientation of the stomata may be parallel to the long axes or occassionally transverse or oblique. So in many of the dicotyledons, the stomata are oriented at randam. While in fern and monocotyledon leaves, the stomata are oriented more or less parallel to the long axes. Rarely, the stomata are oriented perpendicular to the mid-rib. If the orientation of stomata is consistent, then it may be a useful charactor for the identification of certain taxa. THE FORM OE THE EPIDERMAL PELLS AND THEIR WALLS There are no special descriptive terms to indicate the form of epidermal cells and their anticlinal walls. In this investigation shape of the epidermal cells such as triangular, tetragonal, polygonal, irregular, elongated prosenchymatous,

10 37 isodiametric of the epidermal cells are described, The anticlinal walls are described. The anticlinal walls may be thick or thin, sometimes distinctly pitted, straight, arched, curved, lobed arcuate or sinuous. The anticlinal walls may be homogeneous and evenly or unevenly thickened or stratified. The degree of undulations has also been described for anticlinal epidermal walls. The amount of undulations of the cell walls appeared to have of taxonomic significance in certain plant group, although it is a quite variable character influenced by a number of ecological factors. Stace (1965) pointed out these ecological factors. Shading, air, soil and humidity are regarded to cause a stronger undulation of the antidinal walls, the position of the leaf on the stem also seems to be of some influence. Table showing the families studied number of genera and species according to Willis (1966), species studied by previous workers and genera and species studied during the present investigation: Sr.No. Family Genera and Species No. of Gene species according investi- and species to Willis gated studied (1966) of a by during family previous present workers investigati Genara Species Genera Speci 1. Rubiaceae Tognini, (1) Pant & Mehra, 1965(14) Bir-Bahadur et al (26)

11 38 2. Compositae Pognini,1897 (1) Pant & Yerma, 1963(1) Ramayya & Rao, 1968(1) 3. Plumbaginaceae Inamdar and Patel, 1971 (1) Primulaceae Yerma, 1 972(1 ) 4 5. Myrsinaceae Sapotaceae Bhatnagar and Gupta,1969(1) 7. Ebenaceae Scrophulariaceae Orobanchaeeae * Lentibulariaceae Gesneriaceae Bignoniaceae Tognini,1897(1) Inamdar,1969(1 ) Paliwal,1969 (species not mentioned) Pedaliaceae incl. Martyniaceae Inamdar 1969Q Acanthaceae Pant and Mehra, (1) Paliwal,1966(14) Inamdar,1970(31) Yerbenaceae Pant & Kidwai, 1964(1) Inamdar, (14) 16. Labiatae Tognini, 1897(1) Ramayya & Rao 1969(3) Inamdar & Bhatt 1972(32) Plantaginaceae «1 1 Potal ,

12 The data on the past work of these seventeen gamopetalous families has been summarised in the above table. It is very clear from this data that out of 2345 genera and 36,733 species, work has been carried out only on 74 genera and 150 species. Henc there is ample scope for further research on the structure and ontogeny of stomata in these seventeen gamopetalous families. Therefore, the present investigation has been undertaken on the structure and development of stomata on 114 genera and 237 specie belonging to the seventeen gamopetalous families. In addition to these 237 species of 17 gamopetalous families, 3 species of Begonia have also been investigated for comparing the results with those of G-esneriaceae. Therefore, in all 240 species have been worked out.

On the ontogeny of stomata and glandular hairs in some Indian mangroves

Acta Bot. Croat. 61 (2), 199 205, 2002 CODEN: ABCRA 25 ISSN 0365 0588 On the ontogeny of stomata and glandular hairs in some Indian mangroves SAUREN DAS* Agricultural Science Unit, Indian Statistical Institute,