Vernonia lettermannii 'Iron Butterfly' forms vigorous clumps of narrow stems with fine, feathery foliage that are topped by clusters of fluffy, true purple blooms at stem ends in late summer and early fall. Vernonia lettermannii 'Iron Butterfly' foliage resembles that of Amsonia hubrichtii. The blooms are loved by butterflies and is very nice planted with grasses and other late summer blooming perennials.
Vernonia lettermannii, also known as Threadleaf Ironweed, is native to Arkansas and Oklahoma. It is typically found on gravel river bars and nearby rocky outcrops.
Vernonia lettermannii 'Iron Butterfly' prefers full sun and well-drained soil, but is very tolerant of rough, sandy, infertile, dry soils and hot, dry locations. However, it can withstand occasional flooding. Rust resistant.