While we're on the topic of kentuckiense, I've got a question that perhaps Ron et al. could answer. The vast majority of cultivated C. kentuckiense that I see are very distinct. They tend to have extremely dark dorsal sepals and lateral petals. The lateral petals also tend to be relatively short with loose twists. I think every cultivated plant I've seen fits that description. Anyone know the genetic provenance of such plants? IE, from the gulf states? I ask this because the only population I've seen in person (in VA) has plants that look quite different from all other photos I've seen. Long dorsal sepal and lateral petals that are lighter in color and more tightly spiraled.
Yes, I've noticed the same thing while pictures of wild plants show a lot more variation - yellow pouch color, intense spotting on the pouch, lighter sepal/petal color, and even an "alba" form. I suspect that the vast majority of plants in cultivation were derived from limited stock, hence the lack of variation.
Carson Whitlow was the first to artificially propagate this species, starting nearly 30 years ago. His original plant was from the type site in Kentucky, but he mentioned having plants from Oklahoma as well. I suspect these plants formed the first base of available stock, but who knows for sure. I do know he had an impossible time trying to export the species due to CITES regulations and the circumstances under which the original plants were collected.
Nevertheless, plants made it into Europe (no surprise!), but from what source I imagine the response would be mute. I have heard of plants in cultivation from Kentucky, Oklahoma, Louisiana, Texas, and Arkansas. The original plants cultivated were no doubt divisions with mass production of seedlings starting sometime in the mid to late 90's. Germany was the introduction point in Europe. In the states Carson offered divisions throughout the 90's and by late 90's Bill Steele was offering seedlings. Soon after in the early 2000's various nurseries were online selling plants - White Flower Farm, Hillside Nursery, and Vermont Ladyslipper Co., to mention some.
Of course that Virginia population is a disjunctive group, as you well know. There also has been some conjecture that introgression with C. parviflorum v. pubescens is at work with them, hence their unique phenotype.
Direct answer to your question - who knows for sure where the original stock is from? I don't think you'll hear the specifics spoke out loud. Check out Carson Whitlow's article on CITES and the beginnings of this species coming into the broader cultivation scene:
CITES - Blueprint for Extinction. An interesting read whether you agree with him or not.