Defenitely not Aponogeton.
Almost defenitely an Echinodorus sp. There are really many species available to the hobby - and even more hybrids, varieties and cultivars - so giving you an ID from this flower(spike) is not really possible.
Post a pic. of the plant........and a qualified guess of its name, can likely be given.
By the way: you will probably be wieving nice, white flowers coming from the spike soon.