Small white flower (25mm diam) emerging from buds which are densely grouped like grapes at end of branch. Very large green leaves.
Near small pond (Turtle Pond in Central Park), growing near other wild plants/weeds.
Probably not a planting, as it is surrounded by lots of other weeds/volunteers like sorrel and daisies. Looks like a volunteer, but their are plantings of it elsewhere in the park.