The issue was whether speciation occurs gradually, or by a single major change followed by a set of smaller changes. Where the plant originally came from, while relevant to evolution as a whiole, is not germane here. Mutation accounts for the variation; natural selection accounts for its becoming dominant in the population.
If a the original "watch" came from the intervention of an intelligent being then why would you attribute later variation or improvement on a random or un-directed mutation? You are just stating a belief without a foundation.
Whether or not the original plant was made by an intelligent being, we have in this present instance a case where a change in a single allele caused a gross change in the organism, which closely resmbles the change required to generate one known species from another. This argues that there is no necessity to assume intervention by an intelligent being in the present instance