Ornamental-leaf varieties of Ipomoea batatas make potatoes that are just as delicious as the plain leaf, plain species kind but are sold as ornamental. They are foliage sports of the species.
When sweet potatoes are harvested by the home gardener, they often skip the step of curing the potatoes, which makes them sweeter and more tasty.
http://www.motherearthnews.com...
A plant sold as ornamental can be treated with chemicals not safe for use on edibles. For that reason, one might not want to eat plants (or their tubers, in the case of SP's) purchased as ornamentals until/unless enough time has passed so that any systemic 'cides would have had time to dissipate, or whatever the right technical term would be.
