Month: January 2015

Stomata of hornworts (Anthocerotophyta)

Photo credit: Google

Hornwort: Anthoceros punctatus

Stomatal differentiation and abnormal stomata in hornworts

by Pressel S., Goral T., Duckett J. G. (2014)

Silvia Pressel, Tomasz Goral

Jeffrey G. Duckett item21720

in Maney Online: Journal of Bryology, Volume 36, Issue 2 (June 2014), pp. 87-103

http://www.tandfonline.com/doi/pdf/10.1179/1743282014Y.0000000103

Abstract

This light and electron microscope study reveals considerable uniformity in hornwort stomata morphology and density in contrast to common spatial and developmental abnormalities in tracheophytes and mosses.

Stomata arise from a median longitudinal division of sporophyte epidermal cells morphologically indistinguishable from their neighbours apart from the retention of a single chloroplast whilst those in the other epidermal cells fragment. Chloroplast division and side-by-side repositioning of the two daughter chloroplasts determines the division plane in the stomatal mother cell. The nascent guard cells contain giant, starch-filled chloroplasts which subsequently divide and, post aperture opening, regain their spherical shape. Accumulation of wall material over the guard cells and of wax rodlets lining the pores follows opening.

http://www.redorbit.com/media/gallery/national-science-foundation-gallery/medium/183_3a7118b1fc33363e96bafb88b27576fe.jpg
http://www.redorbit.com/media/gallery/national-science-foundation-gallery/medium/183_3a7118b1fc33363e96bafb88b27576fe.jpg

While the majority of stomata are bilaterally symmetrical those lining the dehiscence furrows display dextral and sinistral asymmetry due to differential expansion of the adjacent epidermal cells.

The ubiquity of open stomata suggests that these never close with the maturational wall changes rendering movement extremely unlikely. These structural limitations, a liquid-filled stage in the ontogeny of the intercellular spaces, and spores already at the tetrad stage when stomata open, suggest that their primary role is facilitating sporophyte desiccation leading to dehiscence and spore dispersal rather than gaseous exchange.

Stomata ontogeny and very low densities, like those in Devonian fossils, suggest either ancient origins at a time when atmospheric carbon dioxide levels were much greater than today or a function other than gaseous exchange regulation. We found no evidence for stomatal homology between hornworts, mosses and tracheophytes.

See also: Maney Online

Epidermis morphology and ploidy levels in Buddleja (dicots)

 

Morphological characteristics of leaf epidermis and size variation of leaf, flower and fruit in different ploidy levels in Buddleja macrostachya (Buddlejaceae)

by Chen G., Sun W.-B., Sun H. (2009)

Gao CHEN, Wei-Bang SUN and Hang SUN

in Journal of Systematics and Evolution: Volume 47, Issue 3, pages 231–236, 2009

Abstract 

Buddleja macrostachya (Buddlejaceae) is a widespread shrub native to the Sino-Himalayan mountains and beyond. It has been found to occur at two ploidy levels, hexaploid, 2n=6x=114 and dodecaploid, 2n=12x=228.

To determine if morphological characters might be used as indicators of ploidy levels, we measured floral and fruit length, relative and absolute leaf size, trichome density on both leaf surfaces, and stomatal density and length in different populations of B. macrostachya.

In general, flower and fruit length, absolute leaf size, and stomatal length increased with an increase at ploidy level (P<0.01), whereas adaxial cell and stomatal density decreased with an increase at ploidy level (P<0.01). We found no conspicuous differences in relative leaf size (P>0.05) in different populations.

Other characters studied such as trichome type, cuticular membrane and ornamentation of stomata, cell and stomatal shape, and anticlinal wall pattern were quite constant in this species. Thus it appears that flower and fruit length, absolute leaf size, and stomatal frequency and length can be used to distinguish hexaploid from dodecaploid cytotypes either in the field or in herbarium specimens.

See also: Wiley Online Library

Stomata of Crataegus (dicots)

 

Stomata Size in Relation to Ploidy Level in North American Hawthorns (Crataegus, Rosaceae)

by McGoey B. V., Chau K., Dickinson T. A. (2014)

Brechann V. McGoey, Kelvin Chau, Timothy A. Dickinson

in Madroño 61(2):177-193. 2014
doi: http://dx.doi.org/10.3120/0024-9637-61.2.177

Abstract

The impacts of ploidy level changes on plant physiology and ecology present interesting avenues of research, and many questions remain unanswered. Here, we examine the connections between cytotype, taxon, stomata characteristics, and environmental variables in black-fruited hawthorns of the Pacific Northwest (Crataegus ser. Douglasianae; Maleae, Amygdaloideae, Rosaceae).

We explore the extent to which stomatal measurements can be used to predict ploidy level and how differences in ploidy level and stomata characteristics relate to geographic distributions.

We sampled trees from across the geographic ranges of the putative sister taxa Crataegus suksdorfii (Sarg.) Kruschke (diploids and autotriploids) and C. douglasii Lindl. (tetraploids). We found that stomata differed between the two species, with tetraploid C. douglasii having larger average stomata sizes than diploid and triploid C. suksdorfii.

We also obtained climatological and elevation data for the sites at which these samples were collected, and examined the associations between taxon, ploidy level, stomatal size and density, elevation, and environmental parameters. Our analyses indicate positive associations between stomatal size and latitude, and between ploidy level and elevation.

Negative associations were found between temperature and precipitation variables and both ploidy level and stomatal size, particularly for the fall and winter quarters. There appeared to be no significant association between stomatal density and any of the environmental variables. Tetraploid C. douglasii occupied a wider range of environmental conditions than did either the diploids or the autotriploids.

See also: BioOne

Stomata under microscope

Photo credit: MicrobeHunter

When the glue has dried completely, carefully peel off the glue. It should separate easily from the leaf. The leaf has left an impression on the glue.

Observing Leaf Stomata

http://www.microbehunter.com/wp/wp-content/uploads/2009/stomata3.jpg
http://www.microbehunter.com/wp/wp-content/uploads/2009/stomata3.jpg

It is possible to observe the impression of leaf epidermis cells on white wood glue. The stomata and guard cells are easily visible. The regular shape of the stomata makes it an ideal specimen for practicing drawing.

Read the full article: MicrobeHunter Microscopy Magazine

Stomata during leaf acclimation

Photo credit: Google

Toona ciliata

Acclimation to humidity modifies the link between leaf size and the density of veins and stomata

by Carins Murphy M. R., Jordan G. J., Brodribb T. J. (2014) 

in Plant Cell and Environment 37(1): 124 – 131 – DOI10.1111/pce.12136

https://www.infona.pl/resource/bwmeta1.element.wiley-pce-v-37-i-1-pce12136

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

How various agents work together to form new stomata

 

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

 

Stomata of Hybanthus (Violaceae)

Photo credit: Google

Hybanthus enneaspermus

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

Abstract

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.
See also: Springer Link
Scan
Scan 1
Scan 2

Stomata of Brassicaceae

 

Anatomical characteristics of the epidermis in some cultivars of Brassica oleracea L. distribution and structure of stomata in the cotyledons

by Novotná J. (1976)

Jarmila Novotná

===

in Biologia Plantarum 18(1): 13-18

Screen Shot 2017-04-17 at 13.01.15

Abstract

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.
See also: Springer Link

Morphological types of stomata

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

Abstract

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.
See also: Springer Link

Stomata of Gentianaceae (dicots)

 

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, Volume 101, Issue 7-8, pages 395–400, 1990

Abstract

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