If a personal name ends in a consonant (except -er) then a termination of
two "-i-"s must be added for the proper genitive.

I got that one, but please explain Cedrus libani. It is not a person's name,
but why didn't they call it libanensis or libaniana?
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)