Stomata in fossils


Stomata in early land plants: an anatomical and ecophysiological approach

by Edwards D., Kerp H., Hass H. (1998)

Edwards D., University of Wales Cardiff

Hans Kerp, University of Münster

Hass H., University of Münster

in J. Exp. Bot. 1998, 49(Suppl 1)255-278. –

DOI: 10.1093/jexbot/49.suppl_1.255

CrossRefWeb of Science

Fig. 3. Lochkovian stomata. All SEMs except A–D, I–K (cuticles). (A, B) Dundee Formation, Angus, Scotland (C–M ). North Brown Clee Hill, Shropshire. (A, B) Zosterophyllum myretonianum : typical stoma. Rephotographed from Lele and Walton (1961). Slide 1577 (Hunterian Museum). Bar = 50 m m. (B) Polar indentation suggestive of two guard cells. Slide 1578. Bar = 10 m m. (C ) Fragment with thick ‘epidermal’ ingrowths and isodiametric stoma ( Type A, Edwards and Axe, 1992). NMW90.43G.11. Bar = 60 m m. (D) stoma from (C ) showing cuticularization of epidermal cells in contact with guard cells (arrows). Bar = 10 m m. ( E) surface view of stoma with circular superficial pore. NMW90.43G.9. Bar = 10 m m. (F ) Surface view of elongate stoma ( Type A, Edwards and Axe, 1992). Note superficial lens-shaped pore with further cuticularization below. NMW90.43G.1. Bar = 10 m m. (G, H ) Same stoma viewed from inside (note ‘cradling’ walls of epidermal cells) and out (outer wall of guard cells missing; inner still present, but dropped o ff when cuticle turned over). NMW90.43G.31. Bar = 10 m m. (I ) Cuticularized epidermis in vicinity of stoma, with polar strands (arrow). NMW90.43G.4. Bar = 10 m m. (J ) Cuticularized epidermis in vicinity of stoma with pronounced polar thickenings. NMW90.43G.4. Bar = 10 m m. ( K ) Guard cell cuticle with pronounced thickenings on outer wall near pore. NMW97.37G.4. Bar = 10 m m. (L, M ) Outer and inner surface of outer tissues on axis at base of terminal sporangium of Sporogonites shape. Note cuticular ledge (arrow) on inside (M ) and small pore. NMW96.5G.3. Bar = 10 m m. –

Descriptions of Silurian and Lower Devonian stomata based on cuticles, coalified compressions and permineralizations reveal similarities with those in mosses and certain ferns, and facilitate understanding about the mechanism of guard cell movements.

A detailed survey of stomatal complexes, substomatal chambers and cortical tissues in Rhynie Chert plants suggest adaptations to reduce water loss in peristomatal regions and these, together with a specialized parenchymatous tissue with an extensive intercellular space system at the base of the substomatal chamber, point to high water use efficiency.

Lower stomatal frequencies are discussed in relation to water stress and postulated high atmospheric carbon dioxide concentrations. Stomatal numbers and distribution in axial Silurian and basal Devonian fossils form the basis for speculation on the selective pressures (e.g. the generation of a transpiration stream, H2O and nutrient acquisition, temperature control) that led to the evolution of stomata, although the fossil record provides no direct evidence for evolutionary pathways.

See the text: Web of Knowledge


Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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