Stomata and sterome in fossils

Stomata and sterome in early land plants

by Edwards D., Fanning U., Richardson J. B. (1986)

In Nature 323: 438–440 –


Recognition of pioneering land plants in the fossil record is highly contentious. Because vascular plants possess numerous structural modifications which maintain an internally hydrated environment, attempts to demonstrate the vascular status of megafossils have traditionally dominated research, although more recently evidence from microfossils suggests that Ordovician and Silurian land vegetation may have included plants with some attributes of bryo-phytes1,2 and thallophytes3,4.

Silurian megafossils are preserved as impressions or coalified compressions5, in which anatomy is rarely preserved. The claim to land plant status of Ludlow and Pridoli examples of the presumed rhyniophytes Cooksonia and Salopella is based on their axial architecture, and hence presumed erect growth habit, and on their in situ spores with sporopollenin.

Here we report on exceptionally preserved coalified fossils from the basal Devonian of Shropshire which show that Cooksonia also possessed stomata and thick walled supporting tissues although evidence for vascular tissue still eludes us.

Leaf stomatal frequency and historical levels of atmospheric CO2

Leaf stomatal frequency in the Australian tropical rainforest tree Neolitsea dealbata (Lauraceae) as a proxy measure of atmospheric pCO2

by Greenwood D. R., Scarr M. J., Christophel D. C. (2003)

David R. Greenwood, a Mark J. Scarr, a, David C. Christophel,b

a Sustainability Group, Victoria University of Technology, St Albans Campus, P.O.Box 14428, Melbourne, Vic. 8001, Australia

b Department of Biological Sciences, Room 102 Olin Building, 2190 East Iliff Avenue, University of Denver, Denver, CO 80208, USA


In Palaeogeography, Palaeoclimatology, Palaeoecology 196: 375–393 –


A putative relationship has been demonstrated for European and North American woody dicots and gymnosperms between leaf stomatal frequency and historical levels of atmospheric CO2. However, hitherto no such study has been presented for Australian tropical broadleaved evergreen trees. In this study, variation of stomatal index (SI) along environmental gradients is examined for the broadleaved evergreen tropical rainforest tree Neolitsea dealbata(Lauraceae). Historical herbarium samples from natural populations in northeastern and southeastern Queensland were analysed. Leaf SI for Neolitsea dealbata is shown to be insensitive to mean annual rainfall or seasonal totals, or to temperature variables, indicating the climatic factors that influence the water budget of the plants were not a factor controlling SI. Contrary to the pattern most commonly observed in temperate areas, SI decreased with elevation for collections within a single year for 3 out of 4 years surveyed, a pattern consistent with environmental factors other than pCO2 acting as the control over SI. However, an overall decrease in SI was recorded for samples collected in Queensland (30°–17°S) over the period 1899–1988, corresponding to a Southern Hemisphere increase in pCO2 from 295 to 350 ppm. Restricting the analysis to sites within an altitudinal band of 640–1120 m demonstrated a significant relationship between SI and pCO2(r2=0.8942, F11=84.5, P<0.001). This data set was used to estimate atmospheric pCO2 from fossil leaf cuticle for the closely related genus Litsea, giving pCO2 values comparable to those estimated using Ginkgo from Northern Hemisphere fossil sites.

Moderate levels of Eocene pCO2 indicated by fossil plant stomata

Moderate levels of Eocene pCO2 indicated by Southern Hemisphere fossil plant stomata

by Steinthorsdottir M., Vajda V., Pole M., Holdgate G. (2019)

Margret SteinthorsdottirVivi VajdaMike PoleGuy Holdgate,

1 Department of Palaeobiology, Swedish Museum of Natural History, SE 104 05 Stockholm, Sweden
2 Bolin Centre for Climate Research, Stockholm University, SE 109 61 Stockholm, Sweden
3 Queensland Herbarium, Brisbane Botanic Gardens, Mount Coot-tha Road, Toowong, Queensland 4066, Australia
4 School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia


In Geology 47 –


Reducing the uncertainty in predictions of future climate change is one of today’s greatest scientific challenges, with many significant problems unsolved, including the relationship between pCO2 and global temperature. To better constrain these forecasts, it is meaningful to study past time intervals of global warmth, such as the Eocene (56.0–33.9 Ma), serving as climatic analogues for the future. Here we reconstructed pCO2 using the stomatal densities of a large fossil Lauraceae (laurel) leaf database from ten sites across the Eocene of Australia and New Zealand. We show that mostly moderate pCO2 levels of ~450–600 ppm prevailed throughout the Eocene, levels that are considerably lower than the pCO forcing currently needed to recreate Eocene temperatures in climate models. Our data record significantly lower pCO2 than inferred from marine isotopes, but concur with previously published Northern Hemisphere Eocene stomatal proxy pCO2. We argue that the now globally consistent stomatal proxy pCO2record for the Eocene is robust and that climate sensitivity was elevated and/or that additional climate forcings operated more powerfully than previously assumed.

Developmental and morphogenetic factors govern the evolution of stomatal patterning

Several developmental and morphogenetic factors govern the evolution of stomatal patterning in land plants

by Rudall P. J., Hilton J., Bateman R. (2013)


In New Phytologist 200(3): 598-614 – DOI: 10.1111/nph.12406 –


We evaluate stomatal development in terms of its primary morphogenetic factors and place it in a phylogenetic context, including clarification of the contrasting specialist terms that are used by different sets of researchers. The genetic and structural bases for stomatal development are well conserved and increasingly well understood in extant taxa, but many phylogenetically crucial plant lineages are known only from fossils, in which it is problematic to infer development. For example, specialized lateral subsidiary cells that occur adjacent to the guard cells in some taxa can be derived either from the same cell lineage as the guard cells or from an adjacent cell file. A potentially key factor in land-plant evolution is the presence (mesogenous type) or absence (perigenous type) of at least one asymmetric division in the cell lineage leading to the guard-mother cell. However, the question whether perigenous or mesogenous development is ancestral in land plants cannot yet be answered definitively based on existing data. Establishment of ‘fossil fingerprints’ as developmental markers is critical for understanding the evolution of stomatal patterning. Long cell-short cell alternation in the developing leaf epidermis indicates that the stomata are derived from an asymmetric mitosis. Other potential developmental markers include nonrandom stomatal orientation and a range of variation in relative sizes of epidermal cells. Records of occasional giant stomata in fossil bennettites could indicate development of a similar type to early-divergent angiosperms.

Stomata in Cretaceous fossils

Fig. 3. Ginkgo sp. A, TLM view of two stomatal complexes (SL5572, scale 1⁄4 50 mm); B, TLM view of single stomatal complex with at least four papillae (SL5572, scale 1⁄4 20 mm); C, SEM view of the inner cuticular surface showing one stomatal complex (S-1755, scale 1⁄4 10 mm); D, SEM view of the outer cuticular surface showing one stomatal complex with six papillae (S-1755, scale 1⁄4 10 mm).

Cretaceous plant fossils of Pitt Island, the Chatham group, New Zealand

by Pole M., Philippe M. (2010)

Mike Pole, Marc Philippe,

In Alcheringa: An Australasian Journal of Palaeontology, 34: 3, 231 — 263 – DOI: 10.1080/03115511003659085 –


Fig. 4. Araucariaceae: Araucaria rangiauriaensis sp. nov.; A, SEM view of a single leaf (S-1727, scale 1⁄4 1 mm); B, TLM view of stomatal zone (SL5575, scale 1⁄4 50 mm); C, SEM view of outer surface of a stomatal zone showing obliquely oriented stomata (S-1727, scale 1⁄4 20 mm); D, SEM view of the inner cuticular surface of a stomatal zone (SL5575, scale 1⁄4 20 mm); E, TLM view of typical epidermal cells (SL5575, scale 1⁄4 20 mm); F, TLM view of a single stomatal complex (SL5575, scale 1⁄4 40 mm).


Pitt Island, a part of the Chathams Islands group, lies 700 km east of New Zealand. Its geology includes the Tupuangi Formation, dated as Motuan to Teratan (late Albian to Santonian) on the basis of palynology. Samples of Tupuangi Formation mudstone yielded leaf cuticle assemblages dominated by araucarian and podocarp conifers and locally by angiosperms.

The 12 distinguishable conifer taxa include a new species of Araucaria, A. rangiauriaensis, and the extinct genera Eromangia, Kakahuia (both Podocarpaceae), Otwayia (Cheirolepidiaceae), Paahake (Taxodiaceae or Taxaceae) and possibly Katikia (Podocarpaceae).

Ginkgo and two types of dicotyledonous angiosperm cuticle are present. Based on the absence of bennettitaleans and rarity of Ginkgo, a Turonian or slightly younger age is inferred, making the Pitt Island assemblage the first Turonian plant macrofossils documented from New Zealand.

Fig. 9. Podocarpaceae: Kakahuia sp. A, TLM view showing scattered stomata and prominent papillae (SL5566, scale 1⁄4 50 mm); B, TLM view of a single stomata surrounded by papillae (SL5566, scale 1⁄4 20 mm); C, SEM view of outer surface showing stomata with stomatal pores very subdued (S-1749, scale 1⁄4 20 mm); D, SEM view of inner surface with many stomata (S-1749, scale 1⁄4 20 mm); E, F, TLM views of typical epidermal cells on non-stomatal surface (SL5566, scale 1⁄4 20 mm).

The fossils provide a window into southern high-latitude (polar) vegetation of the mid-Cretaceous. Conifer charcoal (probably of Podocarpaceae) is locally abundant and suggests that fire was an important part of the ecosystem. A broad analogy with modern boreal conifer-deciduous angiosperm forests is suggested although clearly with warmer temperatures

Fig. 11. Podocarpaceae sp. ‘chained’. A, TLM view of stomatal rows. Note darker staining (thicker) subsidiary cell cuticle (SL5642, scale 1⁄4 50 mm); B, TLM view of single stomatal complex showing strong rim. (SL5643, scale 1⁄4 20 mm); C, TLM view of stomatal rows (SL5643, scale 1⁄4 50 mm); D, TLM view (SL5711, scale 1⁄4 50 mm); E, SEM view of outer surface showing stomatal rows with prominent ring of raised subsidiary cells (S-1757, scale 1⁄4 20 mm); F, SEM view of inner surface of a stomatal complex (S-1757, scale 1⁄4 10 mm).

Stomata in fossil Swillingtonia

Description of plate 3
Stomata of Swillingtonia denticulata gen. et sp.nov., and of Aloe haemanthifolia,
photographed by s.e.m.
Figure 19. Part of stomatal band (magn. x 360). V61025.
Figure 20 and 21. Detail of intact stomata. The structures resembling guard cells are here
interpreted as paracytic subsidiary cells, overarching the guard cells proper, compare figure
34a, av 20, (magn. x 810). 21, (magn. x 1350). 20, 21: V61022a.
Figure 22. Partial collapse of outer periclinal walls of subsidiary cells reveals part of underlying
guard cells; compare figure 34a2, (magn. x 1530). V61024a.
F igure 23. Subsidiary cells intact, but guard cells beneath evident through the outer pore (magn.
x 1530).
F igure 24. Outer periclinal walls of subsidiary cells missing (as are those of the encircling cells
at left). Lips of guard cells evident through remains of the outer pore; cf. right-hand side
of figure 34a3, (magn. x 1530). V61021.
Figure 25. Collapse of subsidiary cells (compare figure 34a2) has opened the outer pore to reveal
the stomatal aperture beneath (magn. x 1620).
F igure 26. Stoma of a Recent Aloe haemanthifolia, showing the cuticular ledges simulating guard
cells, as do the subsidiary cells in Swillingtonia (magn. x 1080). From a negative made
available to us through the kindness of Dr D. Cutler. Crown Copyright, reproduced with
permission of the Controller, H.M.S.O. and the Director, Royal Botanic Gardens, Kew.

The earliest fossil conifer from the Westphalian B of Yorkshire

by Scott A. C., Chaloner W. G. (1983)

In Proc. R. Soc. Lond. B 220: 163-182 –

Figure 34. Reconstruction of stomata of Swillingtonia denticulata gen. et sp.nov. (magn.
x 1000). ( a-az). Plan and hypothetical sectional views of the stomata as interpreted in this
paper. This shows the two paracytic subsidiary cells (s.c.) overlying the guard cells (g.c.)
which are visible, in part, through the ‘ outer pore ’ of the stoma. The alternative possibility,
b, blt that the two outer structures are themselves the guard cells is rejected for reasons
given in the text. In the interpretation favoured here, a, ax, the cells shown external to the
subsidiary cells are encircling cells. a2 is a hypothetical section derived from ax, following
collapse of the subsidiary cell outer periclinal walls (compare figure 22). a3 corresponds to
collapse of one subsidary cell and erosion of the outer periclinal wall of the other
(compare figures 24, 25).


Stomata in fossils of South China Sea

Fig. 16. Light microscope photographs of selected stomatal structure morphologies. a, b: large epidermal stomatas; c-d: small epidermal stomatas (possibly broken from the large ones). 

Climatic or tectonic control on organic matter deposition in the South China Sea? A lesson learned from a comprehensive Neogene palynological study of IODP Site U1433

by Miao Y., Warny S., Clift P. D., Gregory M., Liu C. (2018)

Yunfa Miao, Chinese Academy of Sciences

Sophie Warny,Louisiana State University

Peter D. Clift, Louisiana State University

Mitch Gregory,

Chang Liu, Texas A&M University


In International Journal of Coal Geology 190:166-177 – DOI: 10.1016/j.coal.2017.10.003 –


Palynomorphs and other organic particles are basic key components of palynofacies, yet quantitative analyses of all types are rarely used together to investigate organic matter assemblage changes and evaluate the driving forces behind the observed changes. In this paper, eight organic-walled microfossil and particle morphologies (sporopollen, Pediastrum, Concentricystes, fungi, dinoflagellate cysts, structured/amorphous organic matters, stomatal apparatus and scolecodonts) are tabulated and their concentrations and fluxes are evaluated over the past 17 million years (Ma) in sediments recovered from the South China Sea at International Ocean Discovery Program (IODP) Site U1433. Overall, these morphologies show roughly similar increasing trends but with different levels of fluctuations. The uniform increase in all morphologies at ∼. 8. Ma (named the ∼. 8. Ma event) is the most notable feature of the past 17. Ma. To explain the trend, and because these various organic matters reflect various environmental conditions, we argue that the uniformity of the signal implies that tectonically-driven basin and drainage evolution played the key role, rather than paleoclimate (Asian summer monsoon). The ∼. 8. Ma event was likely triggered by the onset of the Mekong River in its present location, although the role of monsoon evolution cannot be excluded completely.