Arrowhead spikes have female flowers toward the bottom, and male toward the top. At least with arumleaf arrowhead, there will occasionally be mid-range flowers of both. Like the one here. Arrowheads provide extra fun because they are good puzzles (at least for me). Identification of some species can be tricky, particularly if you don't have fruit to work with. The tiny spike on the end of the tiny seed will often point you to the right ID. The leaf shape for many species can be extremely variable, and is irrelevant for identification.