"many botanists have studied this strange and bizarre phenomenon from a physiological and systematic point of view, and have written much about Bizzarria. It must be noted, however, that with our knowledge we are almost at the same point as two centuries ago when the strange form of Bizzarria appeared for the first time."[Otto Penzig, Studi botanici sugli agrumi 1887]
When the Italian botanist Otto Penzig summarized the then known knowledge about Bizzarria in 1887, there were two different theories about their origin. A part of the botanists thought it possible that (somatic) cells of the rootstock and of the scion could be fused together by grafting. As a result, a hybrid plant (graft hybrid), such as the bizzarria, can be formed. However, this asexual genesis of a new plant was doubted by many botanists.
Eduard Strasburger, who was at the end of the 19th century intensively involved in herbal fertilization and cell division, also studied bizzaria plants. He noted that the number of chromosomes in the apical meristems of bizzarria sprouts did not differ from those of citrons or sour oranges. In case of a vegetative fusion of the cell nuclei, as assumed by the supporters of the theory of graft hybrids, he would have had to find an increased number of chromosomes. Strassburg excluded the somatic cell fusion during the grafting as the cause of the formation of the bizzarria. As he saw no other explanation, he came to the conclusion that the bizzarria must be a composite sexual bastard, and its special qualities are the result of a "demixing" of its characteristics. Later (after Winklers experiments) he revoked this conclution.
In 1908 the German botanist Hans Winkler run extensive experiments on the question of whether hybrids could arise during a grafting process, and in what way the rootstock and the scion were affected. He succeeded in creation of adventitious shoots from the grafting point of Solanum species, which grew up into new plants. Those showed the properties of the two species involved, but separated in different parts of the plant . Winkler himself called these plants chimeras. He believed that cells of the rootstock und the scion were fusioned by grafting. Subsequent studies showed that the latter was an error. Nevertheless, Hans Winkler is honored to be the first to have proved the formation of graft chimeras experimentally.
Erwin Baur, who had observed similar phenomena in variegated colored Pelargonium at about the same time as Winkler, recognized that in a chimera the tissues of different species or cultivars organize in such a way that they form a common plant (without fusing on cell level).
The evidence of the formation of plant chimera as a result of grafting also brought a new light to the origin of the Florentine Bizzarria as presented by Pietro Nati in 1674.