Diploid and Tetraploid Daylilies

All our daylilies, in cultivation and otherwise, are derived from the wild species native to the Far East. These species all have 11 pairs of chromosomes, for a total of 22 per cell. This is referred to as the "diploid" condition -- from the the Greek "diploos" two-fold. In the scientific context, it means "coming in pairs."

In the twentieth century, biologists learned to treat plant tissues with the natural product colchicine. The action of this drug on the dividing cells of actively growing tissue prevents the cell from completing the process of cell division, but only after the original diploid set of chromosomes has been duplicated.

The resulting plant cells, in the case of our diploid daylilies, now have two sets of 11 pairs of chromosomes, for a total of 44 chromosomes in all. The word "tetraploid" was coined to descibe this new condition -- it means, roughly, having four sets chromosomes.

The tetraploids were considered to be bigger and more robust than their diploid forms, but that need not be the case for every tetraploid compared to every diploid. Indeed, the effects of extensive breeding have long since overwhelmed the simple effects of the chromosome doubling.

For further information, contact us at

Last revised on 5 January 2004
© Copyright 1995, 2001, 2004 James E. Shields. All rights reserved.