Answer: It is usually pronounced just the way we would prnounce it as a woman's name. You can hear a recording of it from The University of Tennessee Department of Plant Sciences web site. You may need to cut and paste the complete url into your browser (and turn up the volume a bit on your pc) to make it work correctly.
However I suppose one could make a case for pronouncing it with the emphasis on the middle syllable as well.
One of my favorite discussions about the pronunciation of botanical names is here:
It is part of the well respected Califlora web site:
I hope this helps.
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