Latin and Greek Meanings and Derivations — A Dictionary of Botanical Etymology
http://www.calflora.net/botanicalnames/, Southern California Wildflowers — Guide to the Pronunciation of Plant Names
http://www.calflora.net/bloomingplants/pronunciationguide.html, Pronunciation of Vascular Plant Genera & Families of New England
http://www.ray-a.com/BotPron/, If you're not able to hear the sound files, click, http://www.calflora.net/bloomingplants/pronunciationguide.html. Www definition at Dictionary.com, a free online dictionary with pronunciation, synonyms and translation. In this case, there are no clear rules on how to pronounce them.