Xenia and Metaxenia

People make mistakes. And too often people are mistaken in accusing others of making mistakes. Here is one example:

Denney, J. O. (1992). "Xenia includes metaxenia". HortScience 27(7): 722–728.

"Although Correns (1899) cites Focke (1881), Swingle [1928] apparently neglected to consult all of the literature, and as a result he did not know that the term xenia applied to pollen effects on parts of the mother plant and that only later did it begin to be applied—somewhat erroneously, as we have seen—to effects on the endosperm. Swingle’s choice of the term “metaxenia” seems to have been questioned from the beginning (Schaffner, 1928), but without apparent effect."

It is apparent to me that it was Denney who failed to review all the relevant literature. East and Hayes (1911) specifically restricted "xenia" to the effects on the endosperm.

"In this older sense the word is therefore of no value, and it may be used solely to describe the visible effect of the second male nucleus on the endosperm. Unfortunately, botanists have not been so prompt in discarding belief in the original meaning of Xenia as the zoologists in discarding telegony."

When Swingle found undeniable evidence of Xenia in the original sense, he could have thrown his facts at East and Hayes, perhaps suggesting rudely that they reconsider their views on Telegony. Instead, he politely ignored their insult and gave the phenomenon a new name.

I think Swingle was too polite, but there is nothing to be done about that. However, I do think it is worth noting that E. M. East was involved in another bit of insulting nonsense, this time involving strawberries.

Mangelsdorf and East (1927) wrote a paper, Studies on the Genetics of Fragaria. Starting on p. 329, they discussed Millardet's "Faux Hybrides". Among other things, Millardet had pollinated a white-fruited Fragaria vesca by a red-fruited F. chiloensis. One of the seedlings resembled the seed parent, except for its red fruit and apparent pollen sterility. The authors wrote:

It seems much more probable that this red-fruited vesca plant is the result of one of several possible forms of contamination. The seed may have been present in the soil in which the sowing was made, F. vesca with the red fruits being the common wild strawberry of France. MILLARDET states that all sowings were made in "terre de bruyère" procured directly from the forest. This practice may have reduced the danger of contamination from foreign seed, but it certainly cannot have removed it entirely.

Another possible source of error comes from trespassing runners. Unless the plants are kept constantly under observation a runner from neighboring plant may, in a very short time, become established on the spot left vacant by the death of the original plant, and once the connection of the intruder with its parent is broken, as usually happens when the bed is cultivated, the evidence as to its origin is destroyed. A third and most probable source of contamination is that of wind-borne pollen.

Stray seed, stray runner, stray pollen. Nothing to see here. Prof. Millardet was a sloppy researcher — and too dead to complain.

But then something happened. East (1930) reported that he had pollinated a white-fruited Fragaria vesca by a red-fruited F. virginiana. One of the seedlings resembled the seed parent, except for its red fruit and apparent pollen sterility. In fact, the plant was a diploid with viable pollen, though the anthers did not open on their own.

East went on the provide solid evidence that his odd seedling was indeed a hybrid, even though it retained no more than seven chromosomes from its octoploid pollen parent.

And of course East made no mention of his earlier paper written with Mangelsdorf, or apologize for insulting the memory of Prof. Millardet.

NB, This was the same Prof. Millardet who invented the Bordeaux mixture that is still used to protect plants.

Swingle: Xenia (1898)
"Xenia, or the communication of the paternal characters to parts of the mother plant in the immediate neighborhood of the developing embryo, was held to be well established in case of some races of maize by the work of Dudley, Savi, de Vilmorin, Hildebrand, Kornicke, Sturtevant, Burrill, Kellerman and Swingle, McCluer, Tracy, Hays, and others, and in case of some races of peas by the work of Wiegmann, Gartner, Berkeley, Laxton, and Darwin."

Bunyard: On Xenia (1906)

East, E. M., and Hayes, H. K. Inheritance in Maize. Conn. Agr. Exp. Sta. Bulletin 167. (Apr 1911)

Swingle: Metaxenia (1928)