Ok, so when in doubt, point to the botany version seems to be the rule! The only one you'd missed, I think, was Pfiesteria piscicida.
Now the task is to try to sort out the articles on botanical nomenclature, so that there is a page "specific name (botany)" to link to (or perhaps a section of an article). At the moment I'm just trying to understand what articles there are and how they interconnect.