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The 'rediscovery' of Mendel's laws in 1900 is seen as a turning point in modern research on heredity and genetics. In the first half of the 20th century it was generally held that the 'rediscovery' was made several times, independently, and in a parallel fashion by three European botanists (Carl Correns, Hugo de Vries and Erich von Tschermak-Seysenegg). Since the 1950s, however, serious questions have arisen concerning both the chronology and the specific conceptual contribution of the scientists involved. Not only the independence but also parallelism was analysed in the context of individual research programmes of all three of these scholars. The youngest of them, Austrian botanist Erich von Tschermak-Seysenegg, was excluded from the rank of 'rediscoverers'. It is the aim of this paper to use new archival evidence and add important facts both to the chronology and conceptual framework of Erich von Tschermak-Seysenegg's work. An entirely new aspect is added by identifying his older brother, the physiologist Armin von Tschermak-Seysenegg (1870-1952), as a significant spiritus movens of the events of 1900 and 1901. A selected part of their correspondence, covering the period from 13 March 1898 until 19 November 1901, is made available in transcriptions., (© 2011 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Ever since existence of sexuality in plants was accepted in around 1700, questions centred about the role and maintenance of sexual reproduction in general, leading to a number of hypotheses like the Vicar of Bray, the Ratchet or the Hitch-hiker theory. Bell (The masterpiece of nature. The evolution and genetics of sexuality. University of California Press, Berkeley, LA, 1982) formulated the Red Queen Hypothesis (RQH) which explains the persistence of sexual reproduction as an outcome of a coevolutionary arms race between hosts and parasites. By sexual recombination and genetic diversification hosts minimize the risk of pathogen infection. Since virulence of pathogens is genetically determined and often species specific, parasites are mostly adapted to common host genotypes, whereas rare and divergent genotypes are less infected and therefore have a selective advantage. Employing Dawkins (The extended phenotype. The long reach of the gene, 1999) central theorem of the extended phenotype to the RQH, mating systems in hosts might be a result of the long reach of the parasites genes. Here now the hypothesis is proposed, that evolution by hybridisation and polyploidy in host plants is an extended phenotype of parasites, a response of hosts triggered by the parasites genes to slow down the effects of the Red Queen strategy of plants. Thus, hybridisation and polyploidy might have evolved by parasite pressure and not by host strategy. This hypothesis is called the "hybridisation-of-the-host-hypothesis".

Information about the topics presented at the 2005 International Botanical Congress (IBC) which was held in Vienna, Austria is presented. The event has featured several research which focus on the evolution of the Rosaceae. A group of researcher has discussed their analysis involving a large data set of molecular sequences, including four chloroplast and six nuclear regions of the said plant species.