Last year I bought the "Dictionary of Plant Names" for $1 on the sale rack at Half Price Books. His suggested scientific pronunciation is KLEM-a-tis. The <a> is pronounced as in <a>part or c<a>nal. He carefully notes scientific names may not be pronounced the same as the English pronunciation! I therefore feel I have scientific approval to say Cle-MAT-tis or whatever else I like!
Like Dahlias. Everyone says it like the a in tally, but since they were named for Mr. Dahl who pronounced his name like "Doll" the scientific pronunciation would be like "Dollia". Nobody I know says this and nobody worries about it.
Who wrote the book: "Allen Coombes is an experienced and highly qualified botanist who worked for the Hillier Gardens in Hampshire, England, and is now coordinator of scientific collections at the University Botanic Garden in Puebla, Mexico. He has written widely on trees and shrubs, was a member of the Horticultural Taxonomy Group for many years, and wrote his first book on plant names in 1985."
Here is my Cle-MAT-is today.
I read a lot and I've always had problems with knowing what words mean but not knowing how to pronounce them. I love the online dictionaries that have the audio files so you can hear the word.
