Stomata in Cycadales


The leaf epidermis of the Cycadales

by Greguss P. (1957)

Botanical Institute of the University Szeged

in Acta Biol. Szeged 3: 181-164. –


FLORI N in his excellent work deals in detail with the leaf epidermis of Coniferae and Cordaites, precisely with the structure of the stomas and he reaches important phylogenetic conclusions.

He describes briefly in his paper the leaf structure of some types of the extinct Psilophyta and Pteropsida, but he does not deal with the leaf-structure of Cycadales, especially the stoma.

We get acquainted with the leaf-epidermis of many extinct Pteridospermae and Cycadales by the recent paleontology findings. They are very difficult to identify as we have no synthetic work which deals with the structure of leaf epidermis of Cycadales, at least by photo. This work intends to retrieve the lack, by describing the structure of the leaf epidermis of living Cycadales and wishes to help the paleontologists at the identification of the paleontology findings.



On studying the structure of leaf epidermis of the characteristic species of the above treated 8 genera more precisely that, of the structure of the stoma located among the epidermis cells thoroughly, it can be stated, that the genera of Cycadales can be differentiated from one another according to the structure of the leaf epidermis.

Their epidermis or stoma structure resembles that of the Coniferales. There are some types e. g. Cycas, which have no similarity with. Coniferales, the stoma structure of which resembles that the air gap is exhibiting craterous structure of Marchantia. The resemblance is really striking!


On the other hand, there are some genera, which show similarity with the stoma structure of the extinct Pteridospermae, e. g. Lyginodendron oldhamium.

The aim of this short paper is to draw conclusion from the comparison of the structuré of the leaf print in fossils concerning the genetic relation with living forms.

The aim of the following detailed communication will be to study not only the structure of the leaf epidermis of Cycadales, but the structure of the leaf’s and stem’s internal organisation too. I hope to publish it soon.


Published by

Willem Van Cotthem

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

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