Ontogeny of the stomata in Gnetum ula Brongn.

The stomata in Gnetum ula Brongn. occur in large numbers on the abaxial surface of the leaves and are orientated in various directions. A few were seen in some preparations on the adaxial surface also, especially in the region of the midrib.
Stomatal development follows the syndetocheilic type of Florin. According to the terminology of ontogenetic types suggested by Pant, they may be described as mesogenous dolabrate; they are mesoparacytic (rubiaceous) and amphicyclic. In this respect, and in several details, the present findings support the observations of Takeda, and differ rather widely from those of Maheshwari & Vasil.
Twin stomata were also met with frequently, as well as several stomata lying together contiguously. The structural features of these are described and commented upon briefly in the paper.     

Systematics value of stomata in some Nigerian hardwood species of Fabaceae

ABSTRACT

Epidermal morphology, and the structure and development of stomata in 10 species of Fabaceae are described. The epidermal cells varied from irregular to straight-walled and in some taxa sinuous patterns were observed. The leaves are hypostomatic. Anomocytic stomata follow an agenous ontogenetic pathway, while paracytic stomata are eumesogenously derived. These stomatal features are considered to be of systematic value in delimiting hardwood species in this family.     

Epidermal Structure and Ontogeny of Stomata in some Verbenaceae

The present paper deals with epidermal structure and developmentof stomata in 14 species of Verbenaceae. The epidermal cellsare either polygonal, isodia-metric, or elongated in variousdirections, and irregularly arranged. The anticlinal walls arethick, mostly sinuous, occasionally arched or straight. Thesurface of the cuticle shows parallel, rarely corrugated, striations.Some 12 types of eglandular and glandular trichomes, and foliarnectaries are noticed. The mature stomata are diacytic, anisocytic,paracytic, with a single subsidiary cell, anomocytic and perigenous.The development of anomocytic stomata is perigenous, while thatof others is mesogenous or syndetocheilic type. Abnormalitiesnoticed here include contiguous stomata, stomata with a singleguard cell, and aborted guard cells.     

Cell kinetics,development of stomata and some effects of colchicine in barley

Summary The developmental sequence of the formation of stomatal complexes in the leaf epidermis of barley was studied. Cell-kinetic parameters were obtained from two genotypes — Early Bonus and eceriferum-g, a mutant with an abnormal stomatal pattern. The distribution of mitotic frequencies as a function of position in the stomatal rows was analyzed at each stage of development leading to mature stomata. Regression curves obtained for each stage showed that the distributions were stage-specific. Thus, the mitotic frequencies presented similar values throughout the portion of the file where the first asymmetrical divisions take place, had a parabolic distribution for the stage of subsidiary formation, and showed a linear shape, with a negative slope, for the stage of guard-mother-cell divisions. The mutant genotype differed from the normal by having a faster rate of ordinary guard-mother-cell divisions as a function of position in the row. The higher level of subsidiary cell formation in the mutant was interpreted as a consequence of a displacement of the used markers, suggesting a precocious initiation of subsidiary-cell formation in eceriferum-g. Time estimations of the length of the cell cycles were obtained by cell-population studies after a pulse with colchicine. Eceriferum-g appeared to have slower cell cycles. The leaves treated with colchicine showed a shift in the elongation axis of the cells. Autoradiography after treatment with ³H-thymidine showed ineorporation of the label in the portions of the row proximal to all three peaks of divisions indicating that all mitoses were preceded by the usual period of DNA synthesis. Labelling of lateral cells at a mature stage suggested DNA synthesis leading to endoploidy.     

Structure, distribution and taxonomic importance of foliar stomata in some Indian Amaranthaceae

The structure, distribution and taxonomic importance of foliar stomata in 45 taxa belonging to 19 genera have been studied. In all, six stomatal types have been recognized viz., anomocytic, anisocytic, diacytic, paracytic, hemiparacytic and brachyparacytic. The majority of the taxa are amphistomatic whereas hypostomatic leaves are confined to only three taxa. Stomatal diversity is common but most of the taxa show either dominance or codominance. Stomatal distribution is helpful in distinguishing the three tribes of the Amaranthaceae. The tribe Celosieae shows exclusive presence of anomocytic and anisocytic stomata whereas Amarantheae and Gomphreneae show other stomatal types viz., paracytic and diacytic in addition to anomocytic and anisocytic stomata. Further, the latter two tribes are each distinguishable into two subtribes on the basis of stomata.     

Structure,ontogeny and taxonomic significance of trichomes and stomata in some Capparidaceae

The present work embodies epidermal structure, structure and ontogeny of stomata in five genera embracing sixteen species of the Capparidaceae namely Cleome (8 species) Capparis (5 species), Cadaba (1 species), Crataeva (1 species) and Maerua (1 species). The epidermal cells are polygonal, isodiametric or elongated arranged irregularly, with evenly or unevenly thickened, sinuous, straight or arched anticlinal walls. Two main types of trichomes: glandular (four types) and eglandular (five types) are noticed. The stomatal types include cyclocytic, triacytic, staurocytic, tetracytic, anomocytic, anisocytic, paracytic and with a single subsidiary cell. The ontogeny of stomata with a single subsidiary cell is perigenous or mesoperigenous, of paracytic mesoperigenous or mesogenous, of anisocytic is mesoperigenous or mesogenous, while that of the other types is perigenous. Abnormalities observed are: single guard cell; aborted guard cells; complete or incomplete division of guard cells; contiguous stomata; giant stomata and cytoplasmic connections. The present observations do not support the separation of Cleomaceae from the Capparidaceae.     

Role of abscisic acid in the closure of stomata in some arid zone plant species

Initially closed stomata in isolated leaf epidermal peelings ofCalotropis procera, Prosopis cineraria andTephrosia purpurea, opened when incubated in distilled water in light or in darkness. Water-induced open stomata closed down on incubation in abscisic acid (0.01 ppm) solution within half an hour. Sodium chloride induced the opening of stomatal aperture. NaCl-induced open stomata also completely closed down when incubated in abscisic acid solution, but open again when transferred to NaCl.     

Structure, distribution and taxonomic importance of stomata in some Indian Tephrosia Pers.(Fabaceae)

SUBBA RAO, J.V.& SHANMUKHA RAO, S. R.(1994).Structure, distribution and taxonomic importance of stomata in some Indian Tephrosia Pers.(Fabaceae).Structure, distribution and taxonomic importance of stomata in all the vegetative parts of 18 taxa of Indian Tephrosia including five species endemic to south India are described. The stomata are anisocytic, anomocytic or paracytic. In addition, brachyparacytic stomata have been recorded for the first time in this taxon. This is the first attempt to assess subgeneric treatment in the light of stomatal characteristics and it suggests certain realignments at the infrageneric level in Indian Tephrosia.     

Biometry of stomata in Blechnum species (Blechnaceae) with some taxonomic and ecological implications for the ferns

Morphological stomatal traits, such as size, form and frequency, have been subject of much literature, including their relationships with environmental factors. However, little effort have focused on ferns, and very few in the genus Blechnum. Stomatal length, width and frequency (as stomatal index) of a number of specimens of fourteen Neotropical species of Blechnum were measured in adult pinnae. The aim of the work was to find biometrical relationships between stomatal traits and between stomatal traits and habit, habitat and ecosystem of the plants. Statistical analyses of data were conducted using Exploratory Data Analysis and Multivariate Statistical Methods. Stomatal length and width showed a very high correlation, suggesting an endogenous, genetic control, thus giving these traits a considerable diagnostic utility. With respect to the relationships between stomatal traits and environment, we found significant statistical relationships between altitude and stomatal index. We also addressed the interpretation of the ecological-selective significance of various assemblages of stomatal traits in a diverse conjunction of habits, habitats and ecosystems.     

Responses of stomata to changes in humidity

Summary Large areas of the lower epidermis of full-grown leaves of Polypodium vulgare (and Valerianella locusta) are normally separated from the mesophyll by an extensive subepidermal airspace. Epidermal stripes were prepared for experiments to simulate these conditions in order to investigate stomatal reactions. They were placed with their inner surface in contact with an airspace of uniformly high humidity. The outer surface was treated with air of varying degrees of humidity. The stomatal reactions were observed by microscope and the opening of the guard cells determined photographically.Treatment of the outer side of the epidermis with dry air led to a rapid closing of the stomata, whilst moist air caused opening. This induction of opening and closing movements could be repeated up to 15 times with the same stoma by changing the degree of humidity. Neighbouring groups of stomata showed different apertures according to their individual humidity conditions. The degree of aperture of the stomata depended on the water potential of the ambient air and also on the humidity conditions in the subepidermal airspace.The cause of this stomatal behaviour could lie in the peristomatal transpiration. In this way, the guard cells are able to function as humidity sensors which measure the difference in water potential inside and outside the leaf. Their aperture thus is controlled by their individual transpiration conditions. This controlling mechanism could be very important for the water economy of plants. They would appear to be able to reduce their transpiration through an increase in diffusion resistance of the stomata during decreasing humidity in the ambient air, without changing the water status of the whole leaf.