The only planet with sweet potatoes

The preschoolers were learning about the solar system. When the teacher got to the third planet from the Sun, she said it had something no other planet in the solar system had and asked if anyone knew what that was.

A boy blurted out, "我知道！我知道！只有地球有地瓜！" -- "I know! I know! Only Earth has sweet potatoes!"

Which is true, as far as we know. The search for extraterrestrial sweet potatoes has so far been fruitless. Or so NASA would have us believe.

In Taiwan (though not in China), the usual word for "sweet potato" is literally "earth-melon," which is presumably what made the boy think of it as characteristically earthly. The other planets then might be home to various unearthly "melons." Some of us were quick enough to read about this in The New York Times before the powers that be memory-holed the story.