 At some time in the past it was split into southwestern (splendid) and southeastern (superb) enclaves.As the southwest was drier than the southeast, once conditions were more favourable, the splendid forms were more able to spread into inland areas.These split into at least three enclaves which subsequently evolved in isolation in the following drier glacial periods until the current more favourable climate saw them expand once again and interbreed where they overlap.