It looks similar to the Closed Bottle Gentian (Gentiana andrewsii) but, according to the USDA range map, this plant is not found in SC and I haven’t been able to find any other pictures on the internet that looks quite like the plants I saw today. There were hundreds of these plants growing near streams and lakes in the Tall Pines WMA where I was hiking on 10/31/21 so I was surprised that I was not able to find any pictures of it.
you probably have Gentiana saponaria. This is the bottle gentian that I see most often along streams in the upstate. It is also one of the very last wildflowers to bloom there.
Dr. Steven Hill, Botanist, SCNPS