What do you call the eggplant cultivar commonly found in American grocery stores?
"The most familiar Eggplants to us, the large dark purple ones, are called "Black Bell" or "Purple Globe." They're also called Globe Eggplant, Western Eggplant and American Eggplant. It's not known who exactly it was that thought this Eggplant was shaped anything like a globe."

http://www.practicallyedible.com/edible.nsf/pages/eggplant#ixzz0yQtZ0gpf