Acharius Medallists

Elisabeth Tschermak-Woess

It is a great pleasure and honour for me to support the award of the Acharius Medal to Professor Elisabeth Tschermak-Woess. There is no question that she deserves this honour, particularly when one considers that she is not really a lichenologist at all. Elisabeth Tschermak-Woess started her scientific career with work on algae, while many of her later publications concern cytological problems in higher plants. She demonstrated, for example, the presence of structural heterozygosity to a surprising extent in natural Allium populations. Together with her co-workers she described the occurrence of polytene chromosomes in plants for the first time. To that date such "giant" chromosomes were believed to occur only in animals.

When she started her cytological work after the war, she had already published papers on the systematics and reproduction of algae and later she returned to this field. The photobionts of lichens were largely ignored by lichenologists or, at best, a typical lichenologist knows four or five different types of algae and the names of these genera are used for anything observed in the thallus. In contrast to this rather superficial classification Elisabeth Tschermak-Woess isolated and cultured all the different photobionts with great care and reported on their diversity in lichens. She was the first to discover a member of the Xanthophyceae in lichens and was able to demonstrate a symbiontic contact of a mycobiont with Chlorella. She described numerous additional genera as photobionts and her work really needs to be recommended and is to be highly appreciated for this treatment of the algae.

One of the well-known problems in lichen reproduction is the relichenization of fungi with Trebouxia. Elisabeth Tschermak-Woess was able to show that these algae may be rare in an unlichenized state but that free-living Trebouxia do occur. Perhaps even more important to lichenology were her investigations on the contacts between algae and fungi in lichens. Only in recent years has this aspect of symbiosis been fully appreciated by lichenologists and many of the recent publications omit to acknowledge the fact that the basic observations were made by her. Her exact descriptions of the different types of haustoria were certainly key discoveries in this field. She demonstrated the difference between intracellular and intramembranaceous haustoria and recognized intracellular haustoria as phylogenetically primitive. The taxonomic relevance of haustoria and the influence of exogenous factors on contact between the bionts were described by her for the first time. The most important results in this field were published as early as 1941 in her dissertation. With the light microscope she observed nearly all the details which were confirmed later with the electron microscope.

Elisabeth Tschermak-Woess has published more than one hundred scientific papers. For many years she has been in charge of the reviews on morphology and development of the cell published in "Progress in Botany". But it is not only the number and quality of these publications, it is above all the broad range of her scientific research that is so impressive.

I have only met Elisabeth Tschermak-Woess twice at congresses but she impressed me very much by her friendly and warm-hearted manner. I would very much like to get to know her better. Perhaps that will still be possible as she is still scientifically active, even though she is now 77 years old. It would have been nice to present her personally with this medal today. Hopefully all of us will be able to give her our personal and cordial congratulations at the next IAL meeting in two years when it will be held in Salzburg.

Sieglinde Ott (19 August 1994)

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