Barb -- that edge is exactly what you said to describe it -- lacy. It's called lace. Irises are said to have lace when they have that finely serrated edge on the (usually) standards. Very often, those same Irises have ruffled petals on the falls. Hence the description -- *ruffles and lace*.
A *wire edge* is different -- it's a thin line of contrasting color on the edges of the standards or falls, or both.
Interestingly, an Iris can have a wire edge on either ruffled or laced petals!
Fun, huh?
