I fail to see the relevance of the reference to the word "fuck" in the pronunciation discussion.  If pronounced with the original German pronunciation, "fook-sya" doesn't sound any more like "fuck" than the word "fork" does and I don't believe the possiblity of mispronunciation as "fuck-sya" is what leads most people to say "fyew-sha" instead. Pronouncing Latinized botanical names based on words and names from non-Latin languages is always going to be a problem, and there is simply no rule in botanical nomenclature that such names must be pronounced according to the rules of pronunciation of their original language.