Erica is a botanical name?! Wow the things you learn on hereCalluna is neat but I thought it was a misspelled attempt at a feminine Callum at first. It reminds me of dogs for some reason.
I think all heathers belong to the Ericaceae family, and there's also a genus named Erica. It's kinda nicer than the "feminization of Eric" meaning. It makes me wish I liked Erica more than Erika. At first glance, I saw Callum in Calluna, too.