Pseudanthium
At a glance, a pseudanthium (inflorescence) looks just like a normal flower, but closer inspection shows it is composed of multiple flowers. Thus, the pseudanthium represents an evolution of the inflorescence to a reproductive unit that may function in pollination like a single flower, at least in plants that are animal pollinated. The advantage of this "flower" is that it produces far more seeds than a normal flower, but needs only one act of pollination.