The significance of Pant’s papers on stomata
by Willem Van Cotthem (Ghent University – Belgium -1981)
In November 1980, Dr. D. D. NAUTIYAL asked the following:
“Dear Dr. Cotthem,
Professor Divya Darshan Pant will be retiring from the Chair of Botany of the University of Allahabad in October 1981 after rendering 36 years of dedicated service. To honour him for his outstanding contributions in palaeobotany, plant morphology, palynology and developmental anatomy, we propose to bring out a special volume containing articles contributed by eminent botanists.
We therefore request you to contribute a paper for the commemoration volume and hope that you will kindly agree. The text should preferably not exceed 15 typed pages and the plates be numbered in pencil. We shall be grateful to receive your consent and the title of the paper by 30th December 1980 and the manuscript by 20 March 1981.
It goes without saying that I accepted this honourable invitation and prepared a paper entitled “The significance of Pant’s papers on stomata”, which I sent to Dr. Nautiyal at 4 consecutive occasions. For unknown reasons it never arrived in Allahabad and I did never got any information on the publication of the “special volume”.
Today, checking old files in my library I discover this paper written in 1980. I cannot resist publishing it here as my personal contribution to the commemoration of Prof. PANT.
The significance of Pant’s papers on stomata
Prof. Dr. VAN COTTHEM W.
Department of Botany – State University of Ghent (Belgium)
To determine the value of someone’s contributions to a certain field of the Sciences can be a very difficult task. Generally, this value can only be estimated a considerable number of years later, when most of the scientists working in the same field have got the possibility to read the publications and to incorporate the data in their own work.
A fairly good idea on the importance of someone’s contributions is given by the number of citations in other papers on the same subject. One could quote the data of the well known CITATION INDEX to show the value of one’s work, although we are convinced that for a number of aspects such an estimation creates only a very incomplete picture, the Citation Index itself staying necessarily incomplete.
However, no botanist studying stomata and their ontogeny, no student working his way through a course on general botany, can deny that the name of Prof. D. D. PANT is to be cited in the short series of illustrious botanists whose publications are real cornerstones in the development of that botanical field.
After VESQUE (1889), FLORIN (1931-1934) and METCALFE & CHALK (1950), PANT was the first and only one to give a decisive impulse to the study of stomatal ontogeny by publishing in 1965 a remarkable survey and brilliant classification of the ontogenetical types of stomata. It corresponds with the starting point of a really impressive series of studies in this interesting scientific field. Both anatomists and physiologists regained soon afterwards new interest in the study of stomata, which was shown by the rapidly increasing number of papers published on this subject.
It can readily be said that PANT’s numerous papers on stomata are of a considerable universal importance.
B. BIBLIOGRAPHICAL REVIEW
In the following survey we will assemble in chronological order the most important data of the publications on stomata of Prof. PANT and his collaborators. This may show how skilled Prof. PANT was in choosing the subjects of his investigations on stomata and their ontogeny. Consequently, one can judge more easily upon the enormous progress made in this botanical field thanks to the contributions of Prof. PANT’s team.
In a remarkable study of PANT & SRIVASTAVA (1962) on the fern genus Isoetes in India, the structure of the mature epidermis was described. The stomata have poorly differentiated subsidiary cells (neighbouring cells ?). These are somewhat tangentially elongated and slightly overlapping the guard cells.
In 1963, PANT & NAUTIYAL gave an excellent account of the cuticular and epidermal structures of the pinnae of 51 species of recent Cycadales. Interesting anatomical details are given for some of them. They also described the sporangia of 14 species belonging to all the genera of modern cycads and the seeds of 18 species belonging to 8 genera. All the sporangia show 2 cuticles and stomata (not present in the sporangia of Cycas and Dioon). In the seeds, 7 different categories of resistant membranes were recorded. The authors determined the constancy of epidermal characters in the 3 types of organs (pinnae, sporangia and seeds) and they discussed their taxonomical value. This remarkable work is the most complete survey of the anatomical structures of the Cycadales and the first to describe exhaustively the stomatal structures of this taxon.
In the same year, PANT & MEHRA (1963a) focused on a number of morphological types in Angiosperms, regretting that only a few ontogenetical studies were available: those on the gramineous type, the cruciferous (anisocytic) type, and the rubiaceous (paracytic) type. Therefore they presented a developmental study on the caryophyllaceous (diacytic) type in Asteracantha longifolia Nees (Acanthaceae).
FLORIN (1933), studying the Gymnosperms, distinguished a syndetocheilic and a haplocheilic type of development and was convinced that the form and arrangement of the subsidiary cells suggest their mode of development. The syndetocheilic type was associated with a paracytic condition of the adult stoma (2 subsidiary cells parallel to the pore and presumably derived from the same mother cell as the guard cells). The haplocheilic type shows always a bigger number of subsidiaries, which are derived presumably from other mother cells than that of the guard cells. The syndetocheilic development of paracytic stomata was also shown in Drimys (BONDESON 1952) and Linum (PALIWAL 1961). PORTERFIELD (1937) did the same for the paracytic stomata of bamboo.
PANT & MEHRA (1963a) were thus the first to express their doubts upon the association of a certain mode of development (e.g. the syndetocheilic one) and a morphological type of an adult stoma (e.g. the paracytic type). They were also the first to show that the syndetocheilic development is not limited to that paracytic type, the caryophyllaceous (diacytic) stomata of Asteracantha longifolia developing in a syndetocheilic way too.
PANT & MEHRA (1963b) gave also a detailed account on the cell divisions leading to the formation of guard cells in Psilotum nudum.
Still in 1963, PANT & VERMA studied the development of stomata in Notonia grandiflora DC. The ultimate anisocytic arrangement of the neighbouring cells (usually 3) suggested the haplocheilic ontogeny (following FLORIN 1933), but PANT & VERMA concluded that the guard cells and neighbouring cells are formed by division of a common mother cell. Their development is thus syndetocheilic (mesogenous) as defined by FLORIN. The authors thereby showed clearly that the adult form and arrangement of the neighbouring cells does not always give a good indication of their mode of development.
In contradiction with FLORIN’s statement that the syndetocheilic development is confined to the paracytic stomata, PANT and his collaborators MEHRA and VERMA were able to describe this developmental type for the diacytic and anisocytic stomata too.
PANT & MEHRA in 1964a completed a series of studies on the ontogeny of gymnospermous stomata (TAKEDA 1913; FLORIN 1931, 1933; MAHESHWARI & VASIL 1961; PANT & MEHRA 1964) in studying that of the stomata of Ephedra. They found that this development was clearly haplocheilic, the subsidiaries (or in fact the neighbouring cells ?) originating from other mother cells than that of the 2 guard cells (in a perigenous way).
The same authors (PANT & MEHRA 1964b), in a study on Cycasand Ginkgo, mentioned again that different earlier papers indicated that the form and arrangement of subsidiary cells in an adult stoma may become considerably altered and may no longer remain a clue to its mode of development. Thus, it became important to study the stomatal development in the living Gymnosperms where it “was previously inferred merely from the topography of their subsidiary cells“.
FLORIN (1931) described a number of conifers with haplocheilic stomata and PANT & MEHRA (1964b) completed our knowledge in this field by studying the stomata in Cycas and Ginkgo. They confirmed that the subsidiary cells are perigenous in origin.
In Cycas most of the encircling cells are formed by tangential division of the surrounding subsidiary cells. the number of subsidiaries and encircling cells increases by formation of radial walls. The cryptopore structure of these stomata is created by the subsidiaries overarching the guard cells. In Ginkgo, the adult subsidiaries become papillate. With this excellent paper PANT & MEHRA provided an important contribution to our knowledge about developmental patterns in stomatal ontogeny of the living Gymnosperms.
Somewhat at the same time PANT & MEHRA (1964c) described the ontogeny of stomata in 3 Ranunculaceae and filled in a gap in our knowledge on the development of anomocytic stomata. The studied stomata originate from meristemoids which give rise to 2 guard cells and 1 or 2 neighbouring cells, while other neighbouring cells are formed from other meristemoids. It is important to note that PANT & MEHRA were the first to describe in this paper a “mesoperigenous” developmental mode in which the neighbouring cells are partly mesogene and partly perigene. They suggested therefore “that the terms syndetocheilic and haplocheilic should henceforth be used only for the two types of gymnopsermous stomata, which are designated by these mainly in the topographic sense“.
Still in the same fruitful year, PANT & MEHRA (1964d) described the ontogeny of the stomata in some fern allies (Isoetes, Lycopodium, Selaginella and Equisetum). In addition to the description of the mature stomata in Isoetes, given by PANT & SRIVASTAVA (1962), the development is called perigenous as the guard cells and the subsidiaries (neighbouring cells ?) are not derived from a single mother cell.
The same ontogenetical pattern was found in Lycopodium and Selaginella. The compound lipped stomata of Equisetum, with mesogenous subsidiaries, were described as quite comparable with the syndetocheilic stomata of the Bennettitales.
PANT & KIDWAI (1964) were the first to mention a record of more than 2 types of mature stomata in the same leaf of one single species (Phyla nodiflora Michx.). Indeed, they found not less than 4 main types with numerous variations in the organisation of the stomatal apparatus: diacytic (48%), paracytic (11%), anisocytic (4%) and anomocytic (3%). In their conclusions PANT & KIDWAI expressed their strong doubts about the taxonomic value of the stomatal characters, particularly in those taxa where the stomata are variable in form and structure. They declared that the constancy of the stomatal characters or their range of variation must be tested in different taxa before using them for taxonomic determinations.
In 1965 PANT gave first some indelible clues to the stomatal development in the mature epidermis of plants before publishing his most valuable contribution “On the ontogeny of stomata and other homologous structures” in the Plant Science Series of Allahabad (1965).
In this remarkable paper a number of developmental types of normal gametophytic air pores of Marchantiales, slime pores of Anthocerotales and sporophytic stomata of other land plants are discerned. PANT discussed the distribution of the stomatal types and their relationships; he suggested that stomata may be homologous to archegonia and antheridia of land plants or to the conceptacles of the Fucales. He even pointed out that, like the conceptacles of the Fucales, stomata too could be regarded as suppressed and specialised branches.
We admired most of all his splendid survey of the main ontogenetic types of stomata: the mesogenous type with its 4 (not 3 !) subtypes (tetralabrate, trilabrate, dolabrate and unilabrate), the mesoperigenous type with its 3 subtypes (Plagiogyria-, Tertacentron- and Ranunculus-type), and finally the perigenous type. One minor remark perhaps: the use of generic names in the terminology could have been avoided (see argumentation of METCALFE & CHALK against VESQUE’s terminology).
It seems to us that this paper of PANT was the most important step forward in the study of stomata and their development. We are deeply grateful to him for showing us the way towards a better understanding of their value in botanical sciences.
Two papers of PANT & BANERJI on the ontogeny of stomata appeared in the same year of 1965. The first one deals with the stomata of Piperaceae (Peperomia and Piper), which are anisocytic or anomocytic and mesoperigenous in development. In the second paper the epidermal structure and the ontogeny of stomata in a number of Convolvulaceae are described. In Merremiaparacytic stomata were found, in Evolvulus they were anisocytic, in Cuscuta invariably anomocytic and in all other plants various types of stomata occured together in the same leaves, but usually in different percentages. In addition to the 3 main types mentioned above, a number of transitional stomata were found. They show intermediate characters between the typical anisocytic and the paracytic stomata. Anisocytic, paracytic and transitional stomata have a mesogenous development, whilst anomocytic ones develop in 2 ways (mesoperigenous and perigenous).
Here again the authors came to the conclusion that the variability of stomata in the same leaf could suggest a weakness in the very use of stomatal characters in systematics. Nevertheless, they recognised that in a lot of taxa these characters are fairly constant. So they recommended a prior study of stomata stability for the use of epidermal characters in systematics. However, PANT & BANERJI accepted that in some cases the instability itself, or the range of instability, could afford a basis for systematic distinction between taxa.
PANT & MEHRA (1965) were the first to study the structure and ontogeny of rubiaceous (paracytic) stomata in the leaves of a large number of Rubiaceae. These stomata have a mesogenous development. In Coffea a number of anisocytic stomata were encountered.
The development of stomata and some interesting anatomical features of leaves, sheating stipules and perianth lobes of some Magnoliaceae (Magnolia and Michelia) were studied by PANT & GUPTA (1966). Most of the foliar stomata are paracytic with 2 subsidiaries and 1 or more parallel encircling cells. The guard cells are partially overlapping the subsidiaries. The development of the guard cells, subsidiaries and encircling cells is typically mesogenous, all developing from the same meristemoid. RAO (1939) showed that the encircling cells are formed by division of the subsidiaries, but according to PANT & GUPTA this is only partly true. In the sheating stipules and perianth lobes the stomata are usually anomocytic. For some of them PALIWAL & BHANDARI (1962) had already described a perigenous development, but PANT & GUPTA were able to show that they are really mesogenous, their development thus being essentially similar to that of the foliar stomata.
In 1966a PANT & KIDWAI published an interesting paper on the structure of the leaves and the stomatal ontogeny in 24 species of the Pandanales and the Spathiflorae. Hypostomatic, amphistomatic (Pistia) and epistomatic leaves (Lemnaceae) were encountered. In Pandanus the stomata are tetracytic (2 parallel subsidiaries, 2 polar subsidiaries, accompanied by 4 triangular encircling cells). In Typha and Sparganium they are paracytic. In the Araceae paracytic or tetracytic and either monocyclic or partly or completely amphicyclic stomata occur. In Pistia and the Lemnaceae they are anomocytic. The authors described furthermore the occurrence of atypical, abnormal and arrested stomata in various species. In all the species studied the development of stomata is perigenous, the subsidiaries, encircling cells and/or the neigbouring cells developing from other initials than the 2 guard cells.
In the same year PANT & KIDWAI (1966b) studied the epidermal structure and the stomatal ontogeny in some Celastraceae, although there exists a rather consistent bibliography on this subject. The authors described, for all the studied species of Celastrus, Elaeodendron and Euonymus, a peculiar type of stomata having a ring of 3 to 8 subsidiaries, covered almost completely by the 2 guard cells, leaving bare only the outer extremities of the subsidiaries. They showed that the sunken subsidiaries of the Celastraceae do not arise by periclinal divisions of the guard cells, like REHFOUS 1914 mentioned, but by anticlinal divisions of perigenous neighbouring cells which initially surround the guard cell mother cells. Their centripetal segments (the subsidiaries) creep under the guard cells, thus forming the two-layered structure of the mature stomata.
A year later, in 1967, PANT & KIDWAI published a study on the stomatal development in 10 species of Cruciferae (Brassicaceae). The anisocytic stomata have a mesogenous trilabrate development. The spiral sequence of the divisions in the meristemoid may be clockwise or anticlockwise. An interesting feature of the neighbouring cells is mentioned: they show very often successive divisions to form new stomata which lie in groups. The same induction of divisions in the neighbouring cells by a meristemoid was already assumed by STEBBINS & JAIN (1960) for the formation of subsidiaries in the otherwise perigenous stomata of Monocots.
Ver rightly PANT & KIDWAI underlined that some unsolved problems remain in the development of the well known stomata of the Brassicaceae. Indeed, we still don’t know which factors are responsible for the sudden change in the division pattern when 2 guard cells are produced by an equational division after a series of unequal divisions to produce the subsidiaries. Likewise, we don’t understand why there is this difference in clockwise and anticlockwise direction of the division sequence in a meristemoid in the same leaf. More experimental work on these aspects seems to be needed.
In 1968 PANT & KIDWAI produced two more papers on stomata. The first one brought a description of the structure and ontogeny of stomata in the Caryophyllaceae. PANT & MEHRA (1963) in Asteracantha and PANT & KIDWAI (1964) in Phyla already described the mesogenous development of the diacytic stomata which are characteristic for the Caryophyllaceae (see also METCALFE & CHALK (1950) “usually of the so-called caryophyllaceous type being accompanied by two subsidiary cells whose common wall is placed transversally to the pore“. In this 1968-paper PANT & KIDWAI showed that not all the diacytic stomata are developed in the mesogenous way. They found indeed a mesoperigenous ontogenetical pattern in which only one of the subsidiaries is formed from the same meristemoid as the two guard cells, the second one being perigene. It is interesting to note that STEBBINS (1965) was able to change experimentally the orientation of the spindle in the dividing meristemoids of Hordeum. PANT & KIDWAI did not succeed in the same experiments with Caryophyllaceae.
In their second paper of 1968 PANT & KIDWAI brought a description of the remarkable development of stomata in Equisetum. A series of papers on this subject gave divergent explanations of the ontogeny so divergent that a detailed study seemed really necessary. The authors came to the conclusion that there is no periclinal wall formation to produce a substomatal cell like so many workers described before. They also concluded that the stomata of Equisetum cannot be regarded as multistratose bicelled pores as was thought by PANT himself (1965) on the basis of a report of CHATTERJEE (1964).
In 1968 PANT & SRIVASTAVA published their observations on the cuticular structure of the seed scales of the fossil Araucaria cutchensis. A series of similarities between this fossil and the modern Araucaria columnaris were registered.
PANT & KIDWAI 1969 studied the ontogeny of the stomata in some Gentianaceae and described for all the species anomocytic or anisocytic stomata, surrounded by a variable number of undifferentiated neighbouring cells. Three main types of development were recorded:
(a) the trilabrate mesogenous type producing anisocytic stomata;
(b) the mesoperigenous type forming stomata with 2 or 1 mesogene neighbouring cell(s);
(c) the perigenous type producing anomocytic stomata with a number of neighbouring cells.
It is interesting to see that the Gentianaceae show all of the stages in the suppression of the number of divisions in the meristemoid before it turns into the guard cell mother cell. The same suppression was observed in other aquatic plants (Lemnaceae, Trapa and Nympaeaceae).
The epidermal structure and the stomatal ontogeny were studied in some eusporangiate ferns by PANT & KHARE in 1969. The 3 genera of Ophioglossaceae show perigenous stomata. Frequently, their neighbouring cells show radial divisions before or after the guard cell formation, thus increasing their number in the ring around the stoma. In Angiopteris evecta (Marattiaceae) the stomata are amphicyclic with a ring of 3 or more subsidiaries, developing in a mesoperigenous way. This statement is in contradiction to the observations of KONDO & TODA (1956) and KONDO (1962). The ontogeny of the stomata is quite similar to that of Piper (PANT & BANERJI 1965a).
In 1971 PANT & KHARE continued their publications on the stomatal ontogeny in Pteridophyta with a paper on the Psilotales (Psilotum nudum and Tmesipteris tannensis). In the 2 species the sunken stomata are anomocytic and their development is perigenous. A certain number of neighbouring cells surround the stoma; these cells occasionally divide radially, thus increasing the number of surrounding cells.
A third paper on the stomata of pteridophytes by PANT & KHARE was published in 1972. It described the epidermal structure and the stomatal ontogeny of 3 Anemia species. In A. tomentosa stomata with 2 to 5 neighbouring cells were observed. Following PANT 1965b they were described as belonging to the ordinary “Lygodium” type (although we were not able to trace this “Lygodium” type in PANT’s 1965b paper). Out of the description of their ontogeny and out of the drawings we deduced that they might be applied stomata (our own polocytic type). In A. phyllitidis and A. rotundifolia each stoma is surrounded by a single ring-shaped subsidiary cell. For this extraordinary type a considerable series of descriptive terms was chosen:
- PRANTL (1881) : stomata libera
- MAROTI (1961) : unicyclic stomata
- MICKEL (1962) : floating stomata (adetostomy)
- PANT 1965 : Anemia type
- VAN COTTHEM (1970a, 1970b) : pericytic stomata
In addition to this “normal” Anemia-type the authors discerned 6 other variations of which the suspended type (our own desmocytic type) and the double floating type (our own duplocytic type) are certainly the easiest recognisable ones. It seems to us that some of their other variations are merely formed by some additional divisions of the subsidiary cell(s) or of the neighbouring cells. Although there might be some minor resemblances with one or another “classical” type of mature stomata, we do not believe that these variations really can be called “paracytic, anisocytic and anomocytic or actinocytic“. The authors themselves declared that these variations all together count for only 8.8 % of the total number, so that it is quite probable that they are not to be distinguished as different types, but as variations of the floating or the suspended type, originated by supplementary divisions in the surrounding cells.
The stomatal ontogeny was studied by PANT & KHARE 1972:
(a) for Anemia tomentosa, where the stomata of the “Lygodium“-type develop mesoperigenously (confirming in that way our supposition that this leads to a polocytic type with one applied mesogene polar subsidiary cell and one perigene neighbouring cell).
(b) for Anemia rotundifolia, where more than 90% of the stomata are of the floating (pericytic) type and the development is mesogenous (Anemia type of PANT 1965b).
The authors formulated an interesting discussion on the possible developmental patterns of floating, double floating and suspended stomatal types.
PANT & KIDWAI 1972, in search of a possible confirmation of the supposed tetralabrate mesogenous development of the stomata in Lactuca virosa, studied the ontogeny of stomata in Lactuca sativa. PANT (1965b) had attributed his tetralabrate type to meristemoids with 4 cutting faces according to the data for the stems of Lactuca virosa (and not L. viscosa !), published by TOGNINI (1897). Apart from a somewhat similar development in some Rubiaceae and Convolvulaceae, PANT had no other indications for the existence of the tetralabrate ontogenetical type than the description of TOGNINI. In Lactuca sativa 89% of the stomata are anomocytic and surrounded by 4 neighbouring cells. The ontogenetical study shows that 2 (or occasionally 1) of the neighbouring cells are mesogene, the other 1 (or 3) perigene. The stomata in this species are thus mesoperigenous. PANT & KIDWAI came to the conclusion that a detailed study of the stomatal ontogeny on the stem of Lactuca virosa is needed to find out if TOGNINI’s description corresponds with the real development.
In 1974 PANT & VERMA analysed the significance of the stem and leaf epidermis and cuticle in a taxonomical study of the genus Ephedra.
PANT, NAUTIYAL & SINGH (1975) described the cuticle, epidermis and stomatal ontogeny of Casuarina equisetifolia. The stomata are transversely orientated in the furrows on the leaves and the stem; they have a mesoperigenous development with 2 lateral mesogene subsidiaries and 2 polar perigene neighbouring cells. Therefore, the authors call these stomata “tetracytic”. It seems to us that the 2 polar cells are only ordinary epidermal cells, happening to be situated immediately against the stoma. We really feel much more for the use of the term “paracytic” in this case, because the 2 lateral subsidiaries are in fact the only ones, together with the guard cells, belonging to the stomatal apparatus. We would like to propose to use the term “tetracytic” only for the stomata with 4 surrounding cells (subsidiaries and/or neighbouring cells) formed by divisions of the stomatal initial and/or its surrounding cells in order to produce a 4-celled ring around the guard cells. However, we must admit that this is only a terminological question and it is of no influence at all on the highstanding character of this excellent study of PANT, NAUTIYAL & SINGH (1975).
NAUTIYAL, SINGH & PANT (1975) studied the epidermal structure and ontogeny of stomata in 3 Gnetum species.
In 1977 PANT & BASU published a comparative study of the leaves of Cathaya argyrophylla and 3 species of Keteleeria. Details of the cuticular, epidermal and anatomical features of these Gymnosperms are given. This study supports the creation of Cathaya as a new genus of the Pinaceae. We learn from it that the stomata are haplocheilic (= perigene ?), commonly monocyclic and then tetracytic, with 4 subsidiaries (or do we have to call them neighbouring cells ?). Occasionally these stomata are amphicyclic (with more than one ring of surrounding cells and thus more than 4 subsidiaries). Sometimes it was difficult for us to deduce of the drawings and descriptions whether these surrounding cells are neighbouring cells or subsidiaries, which shows once more that nature is not always so willing to conform to our rather artificial classification systems.
In order to fill up a gap in our knowledge PANT, NAUTIYAL & SINGH (1978) studied the epidermis and the cuticle of seeds of Gnetum and Ephedra and also those of their inflorescence axes, collars and all the parts of their male and female strobili. For Gnetum ula stomata were found on the vegetative and reproductive axis, in the outer epidermis of the bracts, on the collar, on the perianth lobes of the male flowers and on the outer and middle integument of the ovules (not on the inner one). These stomata are quite similar to those of the leaves (partially or completely amphicyclic with multi-celled rings of subsidiary and encircling cells). For Ephedra a good resemblance between the cuticles of inflorescence axes and those of the vegetative stems (PANT & VERMA 1974) was described. More stomata were found on both sides of the bracts in male flowers, on the perianth lobes of the female flowers, on the outer integument (not on the inner one) and on the nucellus.
If one has to judge upon the importance of the investigations of a scientist and his collaborators in a certain field, one is incited to draw a general table to situate their activities. For the work of PANT on stomata and stomatal ontogeny such a table has to mention the following data:
- PANT 1965a
- PANT 1965b
- Psilotum: PANT & MEHRA 1963b
- Psilotales: PANT & KHARE 1971
- Isoetes: PANT & SRIVASTAVA 1962
- Isoetes, Lycopodium, Selaginella, Equisetum: PANT & MEHRA 1964d
- Equisetum: PANT & KIDWAI 1968b
- Ophioglossales, Angiopteris: PANT & KHARE 1969
- Anemia: PANT & KHARE 1972
- Cycadales: PANT & NAUTIYAL 1963
- Cycas, Ginkgo: PANT & MEHRA 1964b
- Araucaria: PANT & SRIVASTAVA 1968
- Cathaya, Keteleeria: PANT & BASU 1977
- Gnetum, Ephedra: PANT, NAUTIYAL & SINGH 1978
- Ephedra: PANT & MEHRA 1964a
- Ephedra: PANT & VERMA 1974
- Anomocytic stomata
- Ranunculaceae: PANT & MEHRA 1964c
- Anisocytic stomata
- Notonia: PANT & VERMA 1963
- Brassicaceae: PANT & KIDWAI 1967
- Diacytic stomata
- Asteracantha: PANT & MEHRA 1963a
- Caryophyllaceae: PANT & KIDWAI 1968a
- Paracytic stomata
- Rubiaceae: PANT & MEHRA 1965
- Different types of stomata
- Phyla: PANT & KIDWAI 1964
- Piperaceae: PANT & BANERJI 1965a
- Convolvulaceae: PANT & BANERJI 1965b
- Celastraceae: PANT & KIDWAI 1966b
- Gentianaceae: PANT & KIDWAI 1969
- Lactuca: PANT & KIDWAI 1972
- Casuarina: PANT, NAUTIYAL & SINGH 1975
- Stomata of Monocots
- Pandanales, Spathiflorae: PANT & KIDWAI 1966a
Looking at this impressive table, containing 30 papers published in 13 years, one gets aware of the remarkable importance of PANT’s achievements in this field. A considerable number of papers on stomata written by PANT’s collaborators could be added to this table.
All the orders of the Pteridophyta have been studied. Only the large group of leptosporangiate ferns, of which we studied the mature stomata ourselves, was not investigated amply.
Amongst the Gymnosperms, already 30 to 40 years earlier investigated by FLORIN, all the special taxa got PANT’s attention.
For the Angiosperms, his choice of the taxa was determined by the lack of accurate information on the developmental patterns of the different types of mature stomata. It is obvious that PANT paid more attention to the dicots than to the monocots. Nevertheless, taking into account that this survey of PANT’s work on stomata is only based on the publications known in Western Europe, we believe that it can be regarded as one of the most complete achievements in such a short time. It is certainly one of the most important contributions to our knowledge on stomata.
Bondeson W. (1952) – Entwicklungsgeschichte und Bau der Spaltöffnungen bei den Gattungen Trochodendron Sieb. et Zucc., Tetracentron Oliv. und Drimys J. R. et G. Forst. – Acta Hort. Berg. 16: 169-217.
Chatterjee J. (1964) – Stomata in Equisetum ramosissimum Desf. subsp. ramosissimum – Phytomorphology 14: 451-457.
Florin R. (1931) – Untersuchungen zur Stammesgeschichte der Coniferales. Morphologie und Epidermisstruktur der Assimilationsorgane bei den rezenten Koniferen – K. Svenska Vet. Akad. Handl. 10: 1-588.
Florin R. (1933) – Studien über die Cycadales des Mesozoikums. Erörterungen über die Spltöffnungdapparate der Bennettitales. K. Svenska Vet. Akad. handl. 12: 1-134.
Florin R. (1934) – Die Spaltöffnungsapparate von Welwitschia mirabilis Hook. f. – Svensk. Bot. Tidskr. 28: 265-284.
Kondo T. A. (1962) – A contribution to the study of fern stomata. – Res. Bull. Fac. Educ. Schizuoka Uni. 13:239-267.
Kondo T. A., Toda H. (1956) – A contribution to the study of fern stomata. – Res. Bull. Fac. Educ. Schizuoka Uni. 5: 60-80.
Maheshwari P., Vasil V. (1961) – The stomata of Gnetum – Ann. Bot 25: 313-319.
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