Aponogetons, from the African island of Madagascar and Southeast Asia, run the gamut from among the easiest plants to grow to among the most difficult to keep. Aponogetons' bulbs are long and cylindrical with two narrow ends. Leaves sprout from one or occasionally both ends. All of them keep to their natural rhythm of steady, and in some species, explosive growth and look gorgeous for many months, then leaf production ceases. The plant may appear to die back as leaf production slows down. Old leaves may start to die. If conditions are good, new leaves will sprout and grow. In this genus, the rest period lasts a month to six weeks, but nearly all of them insist on that rest period. Due to hybridizing, the rest period isn't as severe as it once was, where the whole bulb was removed when the plant diminished, put in a jar with wet, cold sand and left in a cool dark place for six weeks, only returning it to the tank when growth started. Aponogeton varieties are available in minimum quantities of 12 with most available as bulbs or plants.