I bought this sunflower at a local native plant sale at least 10 years ago. It was sold as Swamp Sunflower (Helianthus angustifolius). A year or two later, we bought another Swamp Sunflower (H. angustifolius), but it looked different. I suspect that one or the other might he H. simulans, which is sometimes called Swamp Sunflower, but more often called Muck Sunflower. Can you ID the plant in the photo, and help me sort out which is which? Online sources either have few or unhelpful photos.
Thanks for all your help,
Virginia in Charleston, SC
I would call this Helianthus simulans, the muck sunflower. The narrow-leaf sunflower, Helianthus angustifolius, has more rigid leaves about half the width. The former is not native in SC, the latter is.
Dr. Steven Hill, Botanist, SCNPS