There is no fact behind the Theory of Evolution in relation to the creation of different species.

The mustard plant was artificially selected to produce different species. The most commonly known species are cabbages, broccoli, cauliflower, rapeseed, and turnips. There are many others. The best thing is that humans created the different species by selecting mustard plants for their stems or leaves or whatever.

Source: http://en.wikipedia.org/wiki/Mustard_plant