Structure and Development of Stomata on the Vegetative and Floral Organs of Some Amaryllidaceae

The structure and development of stomata in 10 Amaryllidaceousmembers are described. The study is made on the leaves and floralorgans of Amaryllis belladona, Crinum asiaticum, C. bulbispermum,C. latifolium, C. pratense, Pancratium sp., Polianthes tuberosa,and Zephyranthes atamsco, and on leaves of Agave sp. and Curculigoorchioides. In most of the organs of the different plants studiedmore than one type of stoma occur, even on the same surface.However, the stomata are largely anomocytic in Amaryllis, Crinum,Pancratium, Polianthes, and Zephyranthes, but they are tetracyticin Agave and Curculigo. An increase in the number of subsidiarycells in teracytic, tricytic, paracytic, and stomata with onesubsidiary cell has been noted. It may be due to wall formationin the subsidiary cells or by the neighbouring perigenes assumingtheir form. The range of variation in different types of stomatain each organ has been studied. Abnormal features such as juxtaposedor superimposed contiguous stomata, connections between guardcells of nearby stomata, transformation of meristemoids intoepidermal cells are observed. The development of different typesof stomata in different organs of the same plant is perigenous.The systematic position of different genera is discussed inlight of the present findings. A method of preparing epidermalimprints by the use of Depex, a mounting medium, and white ofan egg is also described.     

Induction of a 'Periderm-like' Tissue in Excised Roots of the Fern Ophioglossum petiolatum Hook

Basal applications of plant growth regulators to excised rootsof Ophioglossum induce modifications in the outer cortical cells.Benzyladenine initiates periclinal divisions in these outercells producing a ‘periderm-like’ tissue while 2,4-Dcauses cell enlargement only. Walls of the outer cells of the‘periderm-like’ tissue are resistant to sulphuricacid and stain with Sudan IV and presumably are suberized.     

Epidermal Structures and Stomatal Ontogeny in Some Mimosaceae

The structure of trichomes and stomata on leaflets of 21 speciesof the Mimosaceae are described. Non-glandular trichomes inMimosa pudica are of three types: unicellular, with a roundedthick-walled base and a terminal unicellular body, and multicellular.Capitate, clavate, or cylindric, 3–6-celled glandularhairs are observed on leaflets of Mimosa pudica only. Leafletsare amphistomatic in all species except Adenanthera pavonina,Calliandra sp., Parkia biglandulosa, Pithecellobium dulce, andSamanea saman in which they are hypostomatic. Only paracyticstomata are found in Leucaena leucocephala and Mimosa pudica.In the rest stomata are of more than one type. In spite of thediversity, the most frequent type in these species is paracytic.Anisocytic stomata, in all cases, are secondarily derived fromparacytic ones by transverse or oblique wall formation in asubsidiary cell. Similarly some stomata with one subsidiarycell are also secondary derivatives of the paracytic ones becauseof one of the subsidiary cells assuming the form of an epidermalcell. The development has been traced in 14 species and thatof paracytic stomata may be mesogenous or mesoperigenous, thatof stomata with one subsidiary cell mesogenous but anomocyticstomata are ontogenetically perigenous. Occasionally a meristernoidis cut off from one of the subsidiary cells of a paracytic stoma.The organization of a stoma from such a meristemoid has beentraced.     

Epidermal Structure and Ontogeny of Stomata in Vegetative and Reproductive Organs of Ephedra and Gnetum

The epidermal structure and development of stomata in vegetativeand reproductive organs of Ephedra foliata and Gnetum ula isdescribed. The epidermal cells are polygonal, isodiametric,or elongated with thick or thin straight, arched, or slightlysinuous anticlinal walls. The cuticle is thin or thick. Papilla-likeunicellular outgrowths are present in Ephedra foliata. The maturestomata are orientated parallel to the longitudinal axes orirregularly. The mature stomata are anomocytic, paracytic, witha single subsidiary cell, cyclocytic, and actinocytic. Arresteddevelopment, contiguous stomata, and stomata with aborted guardcells have been observed. The ontogeny of stomata on differentorgans of these two plants is typically haplocheilic or perigenousbut the stomatal apparatus varies from organ to organ.     

Ontogeny of Stomata on the Foliar and Floral Or{dot}gans of some Species of Crotalaria L.

The structure and development of stomata in eight species ofCrotalaria belonging to the family Papilionaceae are described.The study is mostly confined to the leaves but it has also beenmade on the floral organs of C. mysorensis, C. retusa, C. sericea,and C. triquetra. The stomata may be paracytic, anisocytic,anomocytic, diacytic, or with one subsidiary cell. The differenttypes occur individually or they are placed side by side evenon the same surface of an organ. In general the paracytic typeis by far the commonest, followed by anisocytic and anomocyticones. Diacytic stomata and those with one subsidiary cell arerelatively rare. Different types of stomata in various organsof the same plant develop mesogenously. The present investigationalso indicates that the inconstancy of stomata in the familyis due to (a) their diversity and (b) an increase in the numberof subsidiary cells either by their division or by the neighbouringperigenes becoming subsidiary cell-like.     

The significance of the Presence of Stomata on Seedling Roots

Slightly squashed and transversely sectioned sprouts (seedlingroot + hypocotyl to cotyledons) of Pisum arvense, Ornithopussativus and Helianthus annuus were examined. The presence ofstomata is described on seedling roots, including the root hairzone, in Pisum and Ornithopus and in the root hair zone of thehypocotyl of Helianthus. The stomata found in the root hairzones are almost always open, usually without chloroplasts andare not sensitive to the action of abscisic acid (ABA). TheABA sensitivity of the stomata appears first above the roothair zone and increases gradually towards the cotyledons. Thepossible role of stomata in the root hair zone is discussed. Seedling root, hypocotyl, root hair zone, stomata     

Structure and Development of Stomata in Some Leptosporangiate Ferns

The structure and development of stomata are described for 17species of leptosporangiate ferns. In these species the maturestomata are anomocytic, diacytic, Pyrrosia(applied), tetracytic,suspended, or floating type. Stomata are present on both surfacesof floating as well as sub merged leaves of Azolla and Marsilea.In a few species twin stomata, arrested development, and persistentstomatal initials are present Floating stomata result from disintegrationof the anticlinal suspending wall in Pleopeltis, and by detachmentand displacement in Azolla pinnata. The development of stomatais haplocheilic, syndetocheilic, or syndetohaplocheilic. InCyathea spinulosa the guard cell nuclei divide amitoticallyand the resulting two daughter nuclei occupy the opposite polesof the guard cells     

Some Observations on the Diversity of Stomata and Trichomes in Six Species of Dioscorea

Stomata and trichomes are described on the leaves of six speciesof Dioscorea. As many as six types were found in D. bulbiferaand D. oppositifolia, four types in D.hispida and D. wallichii,three types in D. belophylla, but only two types in D. alata.Although there is a diversity of stomata even on the same surface,the predominant type is anomocytic in all the species exceptD. bulbifera in which it is tricytic. Rarely a stoma is alsocyclocytic in D. bulbifera. An increase in the number of subsidiarycells in paracytic, tricytic, or diacytic stomata takes placeby the wall formation in them. Similarly a reduction in thenumber of subsidiary cells of a tetracytic stoma is the resultof lateral subsidiary cells assuming the form of epidermal cells.Abnormalities such as a stoma with one guard cell, degenerationof guard cells, and contiguous stomata are also met with. Theorganization of different types of stomata is studied in D.bulbifera and D. wallichii and shown to be perigenous. Capitateglandular hairs were seen on the leaves of D. belophylla, D.bulbifera, D. hispida, and D. wallichii but non-glandular, uniseriate,3-celled trichomes were observed only in D. hispida.     

Functional Stomata in a Variegated Leaf Chimera of Pelargonium zonale L. without Guard Cell Chloroplasts

Fluorescence microscopy indicated that chlorophyll was absentfrom epidermal and guard cells overlying all white areas andgreen areas (of certain leaves) in variegated leaves of Pelargoniumzonale, cv. Chelsea Gem. Stomata with chlorophyll-free guardcells, in general, responded normally to light and CO₂ as gaugedby direct measurements of stomatal aperture and by transpirationalwater loss studies, although stomata from white regions of variegatedleaves were more reluctant to open than stomata from green regionsof the leaves. Thus, functional stomata without guard cell chloroplastshave been discovered in another genus, namely Pelargonium, besidesthat originally discovered in Paphiopedilum. When stomata withchlorophyll-free guard cells opened, K⁺ accumulated in the guardcells. This indicates that chloroplasts are not essential forthe normal functioning of stomata and that the energy sourcefor driving stomatal movements can come from sources other thanphotophosphorylation. Key words: Guard cell chloroplasts, Leaf chimera, Pelargonium, Stomata     

Cellular Interactions in the Development of Stomatal Patterns in Vinca major L

The development of the leaf epidermis of Vinca major L. wasfollowed in situ by epi-illumination microscopy and evidencewas sought for cellular interactions. Stomata were often foundto be initiated in adjoining cells. The epidermal cells whichseparated such stomata when they had matured were formed fromthe same cells as the stomatal complexes themselves. The presenceof developing and mature stomata may influence only the orientationof divisions in neighbouring cells, and not the initiation andmaturation of stomata. There is great variability in the relativeorientation, timing and number of divisions which intervenebetween the first unequal division and the maturation of a stomaas well as the location of stomata relative to the spongy mesophylland minor veins. The results indicate that continuous short-rangeinteractions between the future guard cells and the adjoiningcells, rather than interactions between future stomata or afixed programme of development, are essential for the formationof the pattern of functional stomata in the mature leaf. Vinca major L., cell lineage, cellular interactions, development of stomata, epi-illumination microscopy, meristemoids, patterned differentiation, stomata     

Some Differences in the Responses of Stomata of the Two Leaf Surfaces in Cotton

Some differences in the responses of the upper and lower stomatain cotton (Gossypium hirsutuni) are presented. These differenceswere observed in the course of some studies in which the transpirationof the two leaf surfaces was measured under controlled environmentconditions and the transpiration data used as an estimate ofstomatal response. In darkness the upper stomata were more or less effectivelyclosed while the lower stomata were partially open. Upon illuminationof the leaf with non-saturation or saturation radiation theupper stomata were slower to open than the lower stomata. Thereductions in stomatal aperture which occurs with the increasein age of leaves commenced earlier in the upper stomata andproceeded at a faster rate than the lower stomata. Sudden exposureto saturation radiation caused the stomata of the two leaf surfacesto oscillate. These oscillations were not observed in youngleaves but in older leaves. During ageing of leaves oscillationsof the upper stomata commenced earlier than oscillations ofthe lower stomata. When the petiole was excised in darknessor light the upper stomata showed a transient increase but notthe lower stomata. Gossypium hirsutum, stomatal responses, transpiration     

Giant Stomata

The presence of abnormally large stomata on leaves of Mangiferaindica L. and Limoma acidissima L. is reported. Apart from theirsize, these stomata are indistinguishable from normal stomatapresent on these leaves, and it is likely that they functionin a similar way.     

Stomata of Micropropagated DelphiniumPlants Respond to ABA, CO2, Light and Water Potential, but Fail to Close Fully

Morphological and physiological characteristics of micropropagatedplants of Delphinium cv. Princess Caroline were studied. Leavesproduced in vitro showed poor control of water loss which appearsto result from restricted responses by stomata and not frompoor cuticular development. Stomata of leaves produced in vitrowere larger and more frequent than those produced during acclimatization.Despite the fact that stomata from isolated epidermis of leavesproduced in vitro reduced their apertures when exposed to turgor-reducingtreatments, they did not close fully. This, together with highstomatal frequencies might explain the poor control of waterloss shown by intact leaves produced in culture when exposedto dry air. While leaves from acclimatized plants showed almostcomplete closure with ABA, low water potentials, darkness andCO₂, stomata from leaves produced in vitro reduced their apertureswhen exposed to those factors, but only to a limit. Therefore,stomata from leaves cultured in vitro seem to be partially functional,but some physiological or anatomical alteration prevents themfrom closing fully. Stomata from leaves produced in vitro wereparticularly insensitive to ABA which appears to be partly associatedwith the high cytokinin concentration in the culture medium.In the long-term, this stomatal insensitivity to ABA might contributeto plant losses when micropropagated plantlets are transferredto soil. Key words: Micropropagation, stomatal physiology, dehydration, PEG, ABA, BAP, darkness, CO₂, Delphinium     

Structure and Development of Stomata on the Vegetative and Floral Organs in Some Members of Caesalpiniaceae

The structure and development of stomata in 19 species of thefamily Caesalpiniaceae are described. The study is mostly confinedto the leaves, but observations have also been made on othervegetative and floral organs of some species Stomata may beparacytic, anisocytic, anomocytic, and with one subsidiary cell.Occasionally a stoma is diacytic, cyclocytic, or actinocytic.Different types occur individually or may be found side by sideeven on the same surface of an organ. The most prevalent typein all the genera is paracytic except in Caesalpima where itis anomocytic. The development of an anomocytic stoma is perigenous,but those with subsidiary cells are largely mesogenous; rarelyparacytic stomata are mesoperigenous. In spite of diversityof stomata, different types of stomata have similar patternsof development in different organs of the same plant. The presentinvestigation also indicates that the inconstancy of stomatain the family is due to (a) their diversity and (b) an increasein the number of subsidiary cells either by their division orby the neighbouring perigenes becoming subsidiary cell-like.     

Development of Stomata in Equisetum

Hitherto published accounts of the development of stomata inEquisetum are conflicting about the sequence of divisions andabout the formation of a sub-stomatal cell from a meristemoid.The present study of the development of stomata in a speciesidentified as E. ramosissimum subspecies ramosissimum supportsthe observations of Strasburger (1867) and Pant and Mehra (1964)on the basis of sections cut in various planes through internodesof the plant.     

Variable Development and Cellular Patterning in the Epidermis of Ruscus hypoglossum

The general problem was the meaning of the variability of cellulardevelopment of the stomata-bearing epidermis of Ruscus hypoglossumin which 'immature stomata' occur, i.e. cells that have gonethrough part but not the final stages of stomatal development.The development of the epidermis was followed in vivo, by makingrepeated replicas of the same developing tissues using dentalimpression material. The development of stomata occurred overthe entire surface of large phyllodes and was not synchronous.The early development of future and 'immature stomata' couldnot be distinguished, neither by the form of the cells nor bythe timing of the initial, unequal divisions. The process ofstomatal development did not stop at any one, characteristicsstage. Statistical analyses indicated that the pattern of functionalstomata would have been less orderly if all stomatal initialshad developed into mature structures. The results suggest thatin Ruscus epidermal patterning occurs during, rather than preceding,stomatal development: many stomata are initiated, but they followa labile developmental program and cellular interactions selectthose that reach the mature functional state.Copyright 1993,1999 Academic Press Cellular patterns, epigenetic selection, immature stomata, Ruscus hypoglossum, spacing patterns, stomata, subsidiary cells, unequal divisions     

Stomatal Pattern in Four Species of Monocotyledons

The distribution of stomata has been investigated in the leafepidermis of Chlorophytum comosum, Galanthus nivalis, Schizostyliscoccinea and Scilla lancifolia. The epidermis was consideredto consist of units of construction of two kinds: type A, along epidermal cell with a stoma at its distal end, and typeB, a long epidermal cell without an associated stoma. Exceptin Scilla, the probability of an epidermal unit being type Aincreases approximately with its length. Considering the epidermisas rows of units, alternating sequences of type A and type Bdo not occur randomly along the rows. In Chlorophytum, Galanthusand Schizostylis, both type A and B units tend to be aggregatedinto longer sequences than would be expected on a random basis.It is suggested that homoeogenetic induction (i.e. of like bylike) may be occurring during development. No case can be madefor homoeogenetic induction of units in Scilla. There is a slighttendency to periodicity of distribution of type A units in Galanthus,Schizostylis and Scilla, but this does not seem to representa primary element of pattern. There is interaction between rowsin the sense that unit ends (transverse walls) tend to avoidthose in neighbour rows; this affects the relative distributionof stomata, but there is no evidence of any direct interactionbetween stomata in different rows. Chlorophytum comosum, Galanthus nivalis, Schizostylis coccinea, Scilla lancifolia, leaf, epidermis, stomata, pattern     

Stomata and Structure of Tetraploid Apple Leaves cultured in Vitro

Leaves of anther-derived tetraploid apple (Malus pumila Mill.)shoots were examined by low-temperature scanning electron microscopy(LT-SEM). Leaves were serrate and wide with an undulating adaxialsurface due to convex epidermal cells, apparently without crystallineepicuticular wax. Stomata were absent from the adaxial surface,except for the marginal teeth which exhibited 40-60 stomataper leaf; they probably originated from residual mitotic activity.One third of abaxial stomata was occluded by the residual cuticleof the mother guard cell across the stomatal pore which rupturedwhen the stomata became functional. The stomatal index was 7·2(± 1·6) with 60-75 stomata mm^-2, i.e. abaxialstomata of tetraploid leaves expanded in vitro were less frequentthan those in triploid leaves either cultured in vitro (475-575stomata mm^-2) or grown on the tree (320-390 stomata mm^-2) wherethe stomatal index was 21 (± 4). Freeze-fracture transsectionsshowed that the tetraploid in vitro leaves were composed ofa layer of adaxial epidermal cells, followed by a single layerof palisade cells and four to five layers of spongy mesophyllcells and the abaxial layer of epidermal cells, in contrastto juvenile seedling-grown apple leaves in which the two layersof palisade cells comprised the majority (52-60%) of the leafvolume. The same morphological features, such as wide and lesspointed leaves, reduced stomatal density and stomatal index,and increased stomatal size that were previously reported fortree-grown tetraploid leaves were also expressed in vitro. Thus,causes of the stomatal deformation in tissue-cultured Rosaceaeare interpreted to be in part genetic and not purely environmental.Copyright1994, 1999 Academic Press Malus pumila Mill., apple, biotechnology, breeding, cryo-preservation, CO₂, juvenile, low temperature-scanning electron microscopy (LT-SEM), micropropagation, ploidy, stomata, tissue-culture, transpiration     

Responses of Commelina communis Stomata In Vitro

Weyers, J. D. B. and Paterson, N. W. 1987. Responses of Commelinacommunis stomata in vitro.— J. exp. Bot. 38: 631–641. Analysis of the kinetics of movements of Commelina communisL. stomata in vitro revealed a sequence of opening and closingphases dependent on the incubation medium used and the physiologicalstate of the plant material. In buffer containing 50 mol m ^–3KC1 the sequence of aperture changes appeared to be influencedby equilibration of cell water potentials with that of the mediumand by solute fluxes (dependent and independent on metabolicactivity). The results indicate that the stomatal aperture afterseveral hours of incubation may not always provide a reliablequantitative estimate of the ability of the stomata to operate.As a consequence, modifications are suggested to the ways inwhich experiments using epidermal strips are carried out andreported. Key words: Epidermal strips, guard cells, hydroactive, hydropassive, kinetics, potassium chloride, mannitol, osmotic effects, solute fluxes.     

The Evidence of Stomatal Development on the Relationships Between Davallia and Genera Associated with it by Recent Authors

The structure and ontogeny of stomata occurring on the frondsof Davallia and allied genera, as arranged by Copeland (1947)and Holttum (1947), are investigated. Of the nine types of stomatarecorded, seven are new reports for these ferns. All the ninetypes are mesoperigenous in origin, and pass through eitherthe polocytic or the copolocytic condition during their formativestages. In the hemiparacytic stomata, the long axis of the nuclearspindle in the dividing guard-cell mother cell is always atright angles to the wall first formed by the stomatal meristemoid,and not parallel to it as in all other types. Stomatal structuresupports Holttum's scheme, in which Rumohra (placed in Aspidiaceaeby Copeland) is associated with Davallia, and also his separationof the genera Nephrolepis, Oleandra, Arthropteris and Psammiosorusas a distinct group; among the latter, Nephrolepis rather thanOleandra (Pichi Sermolli, 1977), is shown to be peculiar. Itis also shown that the type species of Paradavallodes (Ching,1966) does not differ from Araiostegia. Davallia, ferns, mesoperigenous, ontogenetic interrelationships, stomatal development