Thank you for your interest. *I hope I can clarify this for you (between you and Fernando I am getting quite a workput in genetics this week, lol).
Drosera anglica is indeed a species, but as with many other true species, it's origin was a result of hybridization. *In this case D. linearis and D. rotundifolia were the parents where they naturally occurr within the same area. *These species are said to be sympatric.
Hybrids are known amongst the temperate species, but such hybrids are typically sterile. *This is because their randomly distributed chromosomes do not line up properly, and the result is defective sperm and eggs. *However, in certain very rare instances, all the genetic material gets included in one daughter cell by accident during the process of meiosis (cell division): one cell has no material, the other has a full set of chromosomes, and is then fertile. Chromosomes can also line up properly through sheer "luck of the draw" and the result is the same. *Such cells have double the original chromosome count, and when these cells divide, each cell has a full set of chromosomes, and in turn are fertile. *This happened in the far distant past with our fertile D. anglica. Chromosome counts show 2N=20 for the respective parents, but in D. anglica they are double that: 2N=40. *There are also sterile hybrids to be found in these habitats which were not so "lucky". *This proscess is assumed to have happened in many parts of the range of D. anglica at many different points in time, and the process continues today where the species are sympatric.
The plant Ivan produced produced by crossing D. linearis with D. rotundifolia would normally have produced sterile seed, because the plant would not have a full set of chromosomes. *When he treated the plant with colchicine, the chemical prevented the formation of the spindle fibers that draw the chromosomes apart during one phase of meiosis, so one cell got none, and the other got a full set of chromosomes. *This is known as amphiploidy, and is one of the most important mechanisms by which new species are formed. *Sterile D. anglica is known as D. x anglica, and it's chromosome count is 2N=20.
I call it prehistoric, because the form of this plant is similar to the very first fertile D. anglica plants! *Evolutionary pressures have not streamlined its form as they have with modern day D. anglica which is both taller and has narrower lamina. *Evolution works by natural selection: survival of the fittest. Those traits which lead to species survival get passed on to later generations. *In this case, I speculate that the wider lamina of these plants created competition amongst themselves for prey and sunlight. *The broad leaves would be more likely to overlap, restricting prey capture. *Taller plants with more narrow lamina were able to lift above the crowd. *They captured more prey, and had more access to sunlight. *They were therefore, better able to thrive, reproduce, and pass these characteristics on to their offspring. *After countless generations, they became more numerous, and the less successful broader leaved forms were out competed: their form was lost as a result, and this is why our present day D. anglica is much different looking than this plant. *The final stage in speciation is reached when the new hybrids can no longer cross back with their progenitors, but it is likely that amphiploidy is responsible for the creation of many of the forms we regard as "true" species.
In this case, there is only one plant on Earth, and it is under my care. *It sort of makes me gulp when I think of it!