This plant is growing at a plantation home in St Francisville, Louisiana. It is about 12″ tall and 15″ wide. They did not know the name of the plant. It has a real appealing smell. They said that they had purchased it from a plant nursery in Louisiana, therefore I am guessing that it is grown here in Louisiana. Thanks for any effort in naming the plant.
I asked some experts, and I was told that this is Viola cornuta “Sorbet Lemon Chiffon”, a fragrant pansy. See: http://www.perennials.com/plants/viola-sorbet-lemon-chiffon.html I generally do not know garden cultivars, but this seems right – there are actually a lot of pages on this on Google. It stands heat and cold better than some of the northern varieties. Pansy flowers are edible, by the way.
Dr. Steven R. Hill, Botanist, SCNPS