labels as words

[Emma May Smith]

That's a great analysis Marco. There is almost certainly going to be a larger element of borrowing among plant names than the text as a whole. (It should be possible to isolate structurally different words as the most likely loanwords.)

However, the lack of [q] in plant names is also seen with star names and zodiac labels. Were all three to have the same source language, that would be fine. Yet it is less likely, if they come from two or more different sources, that they would lack the same characteristics.