All animals and most plants have two copies of each chromosome, one of each from each parent. This diploid status is usually denoted as 2n. Sperm and ova in animals, and pollen and seeds in plants, have only one copy of each chromosome. They result from the final division of a progenitor cell. When that division goes awry and the chromosome number in a pollen or seed cell is not reduced, them a plant with a larger complement of genetic material can result. Plants are able to do this, but not animals.

The Dactylorhiza genus in Britain and Ireland is represented by just two diploid species, Dactylorhiza fuchsii and D. incarnata. Their wide distribution and genetic diversity, evidenced by the range of flower appearance and molecular studies, suggests that they were early colonisers of the British Isles post glaciation. D. incarnata possibly came from Scandinavia over the North Sea bridge (Doggerland as it as been named), while D. fuchsii made its way here from mainland Europe. Once here though, the ancestral species have followed two different evolutionary routes, one being generalist and the other more specialised through varieties.

The genes of the ancestors of these two diploid species provide the genetic make-up of all the British and Irish polyploid species of Dactylorhia; with a few tentative and putative possibilities. I say ancestral because the polyploid events which resulted in the new species took place as recent as around 2,500 years ago to perhaps beyond 30,000 years BP. This is discussed further on.

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