Acclimation to humidity modifies the link between leaf size and the density of veins and stomata
by Gregory Jordan, Madeline Carins-Murphy and Tim Brodribb
in Plant Cell and Environment 2014
The coordination of veins and stomata during leaf acclimation to sun and shade can be facilitated by differential epidermal cell expansion so large leaves with low vein and stomatal densities grow in shade, effectively balancing liquid- and vapour-phase conductances. As the difference in vapour pressure between leaf and atmosphere (VPD) determines transpiration at any given stomatal density, we predict that plants grown under high VPD will modify the balance between veins and stomata to accommodate greater maximum transpiration. Thus, we examined the developmental responses of these traits to contrasting VPD in a woody angiosperm (Toona ciliata M. Roem.) and tested whether the relationship between them was altered. High VPD leaves were one-third the size of low VPD leaves with only marginally greater vein and stomatal density. Transpirational homeostasis was thus maintained by reducing stomatal conductance. VPD acclimation changed leaf size by modifying cell number. Hence, plasticity in vein and stomatal density appears to be generated by plasticity in cell size rather than cell number. Thus, VPD affects cell number and leaf size without changing the relationship between liquid- and vapour-phase conductances. This results in inefficient acclimation to VPD as stomata remain partially closed under high VPD.
See also: Brodribb Lab
Stomata development in plants unraveled
Date: April 3, 2012
Source: VIB (Ghent, Belgium)
Researchers of VIB (Ghent) have unraveled the action mechanism of the main plant hormone that regulates the development of stomata. This breakthrough has important implications for environmental research and for the protection of plants against disease and stress.
Scientific breakthrough: action mechanism deciphered
The VIB scientists are the first to unravel the action mechanism. They were able to determine how the various agents work together to form new stomata. Their experiments showed that brassinosteroids exert direct action on speechless, the transcription factor that initiates the development of stomata. Their action allows for a multitude of different interactions. This exemplifies the strictly orchestrated regulation of stomata development, which is able to react very quickly to environmental changes or internal plant signals.
Read the full article: Science Daily
Photo credit: Google
Epidermal structure and development of stomata in vegetative and floral organs of Hybanthus enneaspermus (Linn.)F. Muell
by Inamdar J. A. (1969)
in Biologia Plantarum, 1969, Volume 11, Issue 3, pp 248-255
The present paper deals with the epidermal structure and ontogeny of stomata in vegetative and floral organs of Hybanthus enneaspermus.
The epidermal cells are either polygonal or elongated with straight, sinuous or arched thick anticlinal walls. The surface of the cuticle shows parallel striations radiating from the guard cells or hair bases. Unicellular and uniseriate bicellular trichomes with verrucose margins have been observed on all organs.
The mature stomata are anisocytic, paracytic, anomocytic and transitional between anisocytic and paracytic.
The ontogeny of anisocytic and paracytic stomata is syndetocheilic or mesogenous, anomocytic is haplocheilic or perigenous, while that of the transitional type is mesoperigenous.
Four types of stomata have been observed on all the vegetative and floral organs and their ontogeny from organ to organ of this plant is constant. Stoma with a single guard cell is the result of disintegration of one of the guard cells before or after pore formation. Contiguous stomata are also occasionally noticed.
Anatomical characteristics of the epidermis in some cultivars of Brassica oleracea L. distribution and structure of stomata in the cotyledons
by Jarmila Novotná
in Biologia Plantarum, 1976, Volume 18, Issue 1, pp 13-18
The blade area and the number of stomata were studied in the cotyledons of five cultivars of Brassica oleracea L., cultivated in a growth chamber and in the greenhouse, respectively. Characteristic differences between different varieties were found in the number of stomata per unit area as well as in their occurrence on both the adaxial and abaxial surfaces.
Historical development of the present classification of morphological types of stomates
by Baranova M. A. (1987)
in The Botanical Review, 1987, Volume 53, Issue 1, pp 53-79
There is a long-standing confusion between morphologic and ontogenetic classifications of stomates. The earliest scheme, by Vesque (1889) was proposed as basically ontogenetic, but it was soon widely applied to mature leaves. The ontogenetic distinction between haplocheilic and syndetocheilic stomates in gymnosperms, proposed by Florin (1931, 1933) soon suffered a similar fate.
Continuing studies over the past half-century have shown that stomatal ontogeny is only poorly correlated with the mature morphology. Efforts to combine ontogenetic and morphologic features in a single scheme have led to classifications so complex as to be impractical. The explicitly morphological classification by Metcalfe and Chalk (1950) is the foundation for the most widely used present scheme, in which some 14 morphological types are recognized. The distinctions among these types are conceptually useful, though often arbitrary in practice.
Epidermal studies in some species of Gentianaceae from West Africa
by Nyawuame H. G. K., Gill L. S. (1990)
Dr. H. G. K. Nyawuame and Prof. Dr. L. S. Gill
in Feddes Repertorium, , Issue 7-8, pages 395–400, 1990
The structure of mature epidermis and the ontogenetic pathway of mature stomata in some species of the family Gentianaceae, viz. Canscora decussata, C. diffusa, Exacum quinquenervium, Faroa pusilla, Neurotheca loeselioides, Sebaea brachyphylla and Swertia mannii are described.
Ontogeny of stomata is shown to be eumesogenous in C. decussata, C. diffusa, N. loeselioides and S. brachyphylla, mesoperigenous in E. quinquenervium and F. pusilla and euperigenous in S. mannii. Juxtaposed contiguous stomata have been observed in C. decussata.
See also: Wiley Online Library
Principles of comparative stomatographic studies of flowering plants
by Baranova M. (1992)
in The Botanical Review, 1992, Volume 58, Issue 1, pp 49-99
Numerous unsolved taxonomic problems have caused systematists to go beyond the traditional methods of herbarium taxonomists and begin to utilize laboratory disciplines such as cytology, palynology, chemotaxonomy, and anatomy. The anatomy of wood and of leaves, among other things, have been used to provide data for systematic studies. The study of the morphology and ontogeny of the stomatal complex in leaves has been one fruitful area for research. The reader is warned that the taxonomic value of such leaf epidermal characters is very different in different taxa just as is true for traditional morphological characters. The terminology used for describing stomates and the whole stomatal complex or apparatus, as it has developed since the time of Vesque (1889) is given. The classifications of Vesque and Metcalfe and Chalk for angiosperms, and that of Florin for gymnosperms are given in detail. The problems inherent in including the ontogenetic development of the stomatal complex in the description and terminology of types are discussed. It is concluded that morphological classification of stomates is best based on their appearance in the mature leaf, excluding any attempt to include ontogeny as well. Fourteen morphological types of stomates are now recognized: anomocytic, anisocytic, paracytic, diacytic, actinocytic, encyclocytic (cyclocytic), tetracytic, pericytic, desmocytic, polocytic, staurocytic, hemiparacytic, laterocytic, and stephanocytic. Other kinds seen in the literature are subtypes of these. In actuality, intermediates between these types exist in nature, and it is not always easy to distinguish these types. Nonetheless, stomatal types and their ontogenies have been used with success in the resolution of many taxonomic problems. The author outlines the many difficulties encountered in the utilization of such data. Even so, examples from the Celastraceae, Chloranthaceae, Polemoniaceae, Hydrophyllaceae, Boraginaceae, Convolvulaceae, Solanaceae, other dicotyledonous families, and some monocotyledonous families are given. The paracytic stomatotype is regarded as probably primitive in both dicotyledons and monocotyledons. Other types of stomates have repeatedly been derived from the paracytic type, so that the presence of similar advanced stomatotypes is not a sure indication of close relationship.