[CholeraJoe]

Why were they after sweet potatoes when they already had yams? They are different species, you know. Yams are native to the South Pacific and Africa but aren't found in great abundance in South America.

[blam]

"They are different species, you know."

Yes, I know. We (in error) call sweet potatoes yams because that's what African slaves called them here in the American south.

I don't know why sweet potatoes migrated west but they did.