The wax is added after it has been removed from the garden.

I've grown two different kinds of grocery store elephant ears. What I've bought as taro root at a regular grocery store turned out to be Colocasia esculenta. These tubers are about the size of a large plum. Nice plants and VERY fast-growing, but they demand a lot of water or their leaf edges turn crispy.

At the local Latin grocery stores, I buy "malanga" which turned out to be Xanthosoma. These are large elongated tubers that sound like the ones you're talking about, although I don't think the ones I buy are waxed. I very much like this plant, and it doesn't demand quite as much water as Colocasia although it's a bit slower-growing.

Here are some pics of my "malanga":

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Sorry for the late reply. Johnnieb, does your malanga return the next year or is that pretty much an annual? They are quite stunning leaves! I've seen malanga here in the Latin stores too although they are not long, actually more oval with one end quite rounded like this site:
http://www.wilderness-survival.net/forage/upload/display/Logos1218629475.jpg
I have seen one that is longer though and I believe they call it taro. The difference, I have no idea.
Perhaps I'll plant all of them to see what the difference is in the plant. Hopefully, none will be aggressive. Let me know if any are!

The long one is probably casava (yucca) root. It will not grow from the root. It grows from cuttings.

I agree that the wax-coated ones sound more like Manihot esculenta, cassava a.k.a. "yuca". The taro, malanga, and yautia "roots" I buy never have a wax coating. Here are the Xanthosoma tubers or rhizomes I buy as "malanga" , also known as "yautia":

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I got 2 different kinds this year, one kind with pinkish flesh (left) and one white (right). I think the pink one is what I've grown in the past; I'm curious to see if the plants from the two different kinds look any different. Taro root, which I find at a different grocery store and has always grown into Colocasia esculenta for me, is smaller and less elongated.

No elephant ears of any kind have ever survived a winter for me.