I had occasion to call Mike Trzonkowski of Delaware Aquatic Imports (the plant guy) and we spent a fair amount of time discussing Aponogetons. I have a list here of resting period times and pointers on Aponogeton culture that you may find interesting.

The aponogetons are unique in that they go through a resting phase.

Actually they go through several phases: vegetative, when leaves are produced, reproductive, when flowers are produced, and dormant when the plant rests. The vegetative phase is easy to discern - that's when your plant throws up leaves. It may or may not flower; it may just idle when it would normally flower. When it sheds it's leaves and doesn't put up any new ones, it's hibernating.

Some aponogetons will rest in your tank without any intervention, but most require semi-dry storage, out of the tank. To store these bulbs, mix potting soil and clean sand or gravel half and half, and adjust the wetness until its not overly damp, but not bone dry. A little more damp than pipe tobacco; about what you would use for storing Nothobranchius eggs.

Once this is prepared, remove the tuber from the tank and remove all dead leaves, and any dead parts such as loose dead roots, or loose leathery parts of the tuber. If it stinks to high heaven - usually hydrogen sulphide - you may try to salvage it by washing it thoroughly, although I don't fancy your chances. I use a baby food jar and place the tuber in the middle of the jar so there are equal amounts of gravel/dirt on top of and below the tuber. The bulb is put in a cool (not the fridge!) dark place for 3 - 4 weeks. After hibernation it is placed back in the aquarium in a rich substrate.

The tuber is where the plant stores food in the form of starches for the next season. In theory, the tuber should get bigger every year. If it doesn't, this means your plant is drawing on it's stored reserves for food rather than nutrients in the substrate. Clay is one of the best things for aponogetons; they like a very rich (and calcium free) substrate.

The tuber is why an aponogeton will do well in a bare tank with no food. It will grow for about 6 months, but by then it has exhausted it's food supply and will probably just die off. Most aponogetons probably die in this manner.

The following species will rest in your tank without any action needing to be taken:

        Aponogeton crispus 
        Aponogeton rigidifolius (it has no bulb, just a rhizome) 
        Aponogeton stachysporous 

The following species need a dry resting phase:

        Aponogeton biovinanus 
        Aponogeton elegans 
        Aponogeton elongatus 
        Aponogeton madagascariensis (both wide and narrow leaf forms) 
        Aponogeton ulvaceous 
        Aponogeton undulatus 

Mike lists two other species on his list: Aponogeton natans and Aponogeton capronii. When I asked how to incubate natans, he said ``who cares''. Natans produces floating leaves, so it is not common, and is used only for cover. The few submersed leaves it produces look like feeble ulvaceous leaves - indeed they are often passed off as ulvaceous. The real ulvaceous does not produce floating leaves. The other neat one is capronii. The leaves are reddish-brown-olive-green, and shaped like spiral pasta. It's slow growing, and nothing is known of it's hibernation habits. It's *expensive*. Mike lists lace plants for $6, but capronii is $9. Double this for store prices.

What happens if you don't remove a tuber that requires dry incubation ? In my experience they rot and that's it. Game over.

To be honest, I have had some come back after a resting period but not with any degree of vigor.

This is also about a comprehensive list of Aponogetons as you will find. The only ones not here that I've seen elsewhere are;

        Aponogeton nana - dwarf lace plant - huge tuber small plant 
        Aponogeton echinatus 
        Aponogeton distachys - water hawthorn - outdoor plant - huge 

Some names that are now considered invalid:

        Aponogeton bernarius 
        Aponogeton henkalinaius 

These are felt to be populations of A. madagascariensis.

There really is no good book on these plants. By good book I mean a book that lists ALL the species, and has good pictures of each one. About the best book is Rataj and Horeman's, but it doesn't list several of these species, and insists that stachysporous is undulatus, whereas Mike has two definitely different plants under those names.

Richard Sexton Oct 17 1989