ironweed Interesting Notes. Vernonia lettermannii 'Iron Butterfly' is a selection of the Arkansas native coming to us from Dr. Allan Armitage's trials at the University of Georgia. It has lovely fine foliage like Amsonia hubrichtii and is a compact, well-branched and vigorous plant.In late summer, 'Iron Butterfly' is dramatically covered with true purple flowers that attract plenty of. About Reverse Iron Butterfly Spread The Reverse Iron Butterfly Strategy is an options strategy and it yields limited profit as the risk of a limited nature. Market bet rests on the price movement of an underlying stock, which will need to move by a sharp margin. Thus, it is a strategy that can be played in volatile market conditions.