The attractor of the iterated function system given by the set of "fern functions"

			(1)
			(2)
			(3)
			(4)

(Barnsley 1993, p. 86; Wagon 1991). These affine transformations are contractions. The tip of the fern (which resembles the black spleenwort variety of fern) is the fixed point of , and the tips of the lowest two branches are the images of the main tip under and (Wagon 1991).