Artificial plant hybridization as a repeatable experiment
Crossing of plants set up as a repeatable experiment: pollen is transferred by hand, crosses are counted, a cross is compared with its reciprocal, and successive generations are followed.
This setup was introduced in 1761 by the German Joseph Gottlieb Kölreuter. From his experiments came three results that would be tested for the next hundred years: the first hybrid generation is uniform, a cross and its reciprocal give the same outcome, and the offspring of hybrids are no longer uniform but tend back towards the parental species. By the count given in the review by Kopecký, Martín and Smýkal he made more than five hundred crosses on 138 species.
The experiments were made for the sake of the question of sex in plants and of the limits of the species, but they left behind a ready technique used both by horticulturists and by later students of heredity.
Why this date
The date follows the first publication. 'Vorläufige Nachricht von einigen das Geschlecht der Pflanzen betreffenden Versuchen und Beobachtungen' appeared in Leipzig in four parts between 1761 and 1766; the first successful hybrid, Nicotiana rustica × N. paniculata, is described in the 1761 part. The dating and content are taken from Robert Olby's article on Koelreuter in the Dictionary of Scientific Biography; the volume and pages of the printed DSB could not be checked, the article was read in the electronic reprint at encyclopedia.com.
What grew out of it
-
'Versuche über Pflanzen-Hybriden': segregation of characters and numerical ratios
influenced · Confidence: high
Mendel worked inside the research tradition of the hybridizers opened by Kölreuter: he took from him both the subject (the reversion and transformation of hybrids in later generations) and the design of the experiment, and himself acknowledged the part his work played in his own research.
Dispute: The continuity of technique and subject is not in dispute; what is in dispute is the meaning of the borrowing. For Olby and for Müller-Wille with Orel, Mendel's naming of Kölreuter and Gärtner in the introduction and again in the discussion of the 1866 paper is an argument that he belonged to the tradition of the hybridizers and was working on the origin of species through hybridization. Van Dijk and Ellis (2023) contest that reading and hold the link to the hybridizers to be methodological, Mendel's own problem being a different one. Separately: the Olby quotation 'Mendel, Sprengel, and Darwin owed him a debt' is taken from the electronic reprint of the Dictionary of Scientific Biography at encyclopedia.com; the volume and pages of the printed edition could not be verified.
Link sources
- Hui Zhang, Wen Chen, Kun Sun, Mendelism: New Insights from Gregor Mendel's Lectures in Brno, Genetics 207 (1), 1-8 (2017)
Mendel admitted that the work of the German scientist Kölreuter on plant hybridization had played an important role in the development of his own research (Mendel 1866).
- Hui Zhang, Wen Chen, Kun Sun, Mendelism: New Insights from Gregor Mendel's Lectures in Brno, Genetics 207 (1), 1-8 (2017)
It is clear that Mendel had the same research interest as his predecessor Kölreuter in hybrid fertility and in the tendency of hybrids to revert or transform in subsequent crosses.
- Robert Olby, Koelreuter, Joseph Gottlieb, Complete Dictionary of Scientific Biography (1973) Verified 20 Sep 2026
Mendel, Sprengel, and Darwin owed him a debt.
- Peter J. van Dijk, T. H. Noel Ellis, Gregor Mendel and the theory of species multiplication, Genetics 224 (2), iyad046 (2023)
An important argument for Olby (1979), Brannigan (1979), and Müller-Wille and Orel (2007) to place Mendel in the tradition of the hybridizers, who were concerned with the question of whether species could arise through hybridization, was that Mendel explicitly mentioned these hybridists in the introduction and again in the discussion of the 1866 article.
- David Kopecký, Antonio Martín, Petr Smýkal, Interspecific hybridization and plant breeding: From historical retrospective through work of Mendel to current crops, Czech Journal of Genetics and Plant Breeding 58 (3), 113-126 (2022) Verified 20 Sep 2026
He also showed that F1 hybrids are usually morphologically intermediate relative to their parents and that successive generations tend to revert back to the parental forms.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Hui Zhang, Wen Chen, Kun Sun, Mendelism: New Insights from Gregor Mendel's Lectures in Brno, Genetics 207 (1), 1-8 (2017)
Node sources
- Robert Olby, Koelreuter, Joseph Gottlieb, Complete Dictionary of Scientific Biography (1973) Verified 20 Sep 2026
he discovered the uniformity and almost complete sterility of these plant hybrids, the identity of reciprocal crosses, and the contrast between these hybrids and their progeny. The latter were not uniform but tended to return to one of the parental species.
- Robert Olby, Koelreuter, Joseph Gottlieb, Complete Dictionary of Scientific Biography (1973) Verified 20 Sep 2026
His first success was with the cross Nicotiana rustica X N. paniculata
- J. G. Kölreuter, Vorläufige Nachricht von einigen das Geschlecht der Pflanzen betreffenden Versuchen und Beobachtungen, nebst Fortsetzungen 1, 2 und 3, Leipzig (1761)
Vorläufige Nachricht von einigen das Geschlecht der Pflanzen betreffenden Versuchen und Beobachtungen
- David Kopecký, Antonio Martín, Petr Smýkal, Interspecific hybridization and plant breeding: From historical retrospective through work of Mendel to current crops, Czech Journal of Genetics and Plant Breeding 58 (3), 113-126 (2022) Verified 20 Sep 2026
Kölreuter made over 500 crosses involving 138 species such as Nicotiana, Dianthus, Matthiola, Hyoscyamus and Verbascum.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.