They all do, although sometimes the flowering head sits down in the center of the leaf rosette. There are many kinds and some look different from one another but are actually in the same genus - when there aren't even flowers present accurate identification may not be very likely.

A good hint that flowering has occurred is when the rootstock produces multiple new rosettes around the original one, which eventually then collapses. One idea is that this Doctor Who style cycle serves to provide some organic matter to a plant that is otherwise gripping a more or less bare tree branch in nature.