And, of course,finally we get to plants like the mosses and Eriocaulons that are very, VERY difficult to determine. In some cases, like E. parkeri, we could get a determination because there aren't too many Erios in that region. In places like India? Good luck. There is a different one in every stream. Often things get into the hobby LONG before the scientists have time to figure out what they are. That is also what is happening with Bucephalandra.
In the case of chain swords, (which, BTW, were removed from the genus, Echinodorus a long time ago now, even though many growers still use the wrong genus... They are now Helanthium) I have seen three distinct types of H. tenellum. One has consistently short green leaves, one has consistently short leaves that turn red in bright light, and one has green leaves that grow quite a bit longer in poor light. I can't tell you whether these were different collections from the wild (most probable, since these plants have been in the hobby in these three forms for many years) or whether they diverged in the greenhouse somewhere.
The problem is, very few botanists have any direct contact with, or for that matter, particular interest in aquarium plants (funnily enough, most botanists work mostly from dried materials, even in this day and age) So you have to find someone who has the expertise, the interest, the TIME and the funding to take it on. Even then it takes time.