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The Aponogeton Family

by Karen A. Randall <76535.2776-at-compuserve.com>

The Aponogetons are a truly aquatic genus with species distributed throughout the tropical and subtropical regions of Africa, Asia and Australia. There are a number of different species of Aponogeton available in the hobby these days as well as many hybrids.

You can at least get a clue to the ancestry of an unknown plant by looking at the flower spike. An Aponogeton from Asia will have a single bloom, while those with African heritage (including Madagascar) have multiple blooms on the same stalk. Most Asian species remain submerged year round, while the starchy tubercles of the African species are able to survive the dry season by shedding their leaves and going dormant. Most Asian species have a dormant period too, but this is temperature related, not a response to drought conditions.

Aponogetons are somewhat variable as far as difficulty are concerned. Most of the more common "pet shop" plants are very forgiving, and make excellent beginner plants, while some, such as the Madagascar Lace plant can be extremely demanding.

The most common and least expensive varieties ar sold as "wonder bulbs" or Aponogeton crispus. Most of the plants sold under the name crispus are actually hybrids, very often crispus x natans. The true crispus has reddish leaves and never develops floating leaves, while most available in the hobby are green plants which may or may not develop floating leaves. Crispus or not, these are very desirable plants for the beginning aquatic horticulturalist. They are very undemanding in terms of water conditions and lighting. Given a reasonably clean environment and marginal lighting, they will grow into a good size attractive plant, and will even be very likely to produce flowers. Another advantage to these hybrids is that many do not go though the dormant period common to most of the species, or will complete a short dormant period in the tank and re-sprout on their own.

In addition to the common hybrids, there are a number of Aponogeton "species" available these days. Again, many of these have been hybridized to have the good looks of the desirable species, while being hardier and easier to care for in the aquarium. Some of these are exceptionally striking plants. You may be able to find these plants from time to time in pet stores. If not, you can most certainly get them from mail order sources.

Aponogeton ulvaceous
This is an exceptionally beautiful species. It is a very large plant with very wide wavy edged leaves in a bright lime green color. It comes from Madagascar, and is happiest in a strong water flow. A good place for it is in front of the outflow of a power filter. Iron fertilization is necessary for good growth, and the plant does require a rest period. It has attractive yellow double-spiked flowers that are self-fertile.
Aponogeton rigidifolia
A. rigidifolia, which comes from Sri Lanka, is different from most Aponogetons in several ways. Instead of a tuber, the plant grows from a rhizome. Up to ten plants can originate from a single rhizome. It has long strap like leaves with edges that are only slightly ruffled. The color ranges from deep green to olive brown. Rigidifolia does not require a rest period, as there is no storage system. It is a stately plant that requires excellent water conditions to remain at its best. It prefers water with a little greater hardness than some, and does not like to be moved once it is established. Propagation of this species is by rhizome division.
Aponogeton madagascarensis
This is, of course, the well known "Madagascar Lace Plant". As its name implies it is a Madagascar native, and endangered in the wild due to habitat destruction. Fortunately, most plants available commercially in this country have been captive grown. For those who are unfamiliar, this plant is a knock out. It has extremely unusual leaves. The tissue surrounding the vein structure is completely missing, so each leaf looks like a beautiful piece of dark green lace. The problem is that the plant is extremely difficult to grow. It requires absolutely clean water, and no algae. Algae settling on the leaves will quickly kill the plant. It needs cool water from 62-68F and will not tolerate boisterous fish. Most people who manage to keep it alive do so in a tank devoted to just that plant. That said, I have heard of several people who successfully keep and propagate this tank with no special care. According to a major European plant grower, about 90% of plants collected fail to thrive in aquariums even under the best of conditions, while the remaining 10% settle in and can grow into a magnificent display. Since this is a fairly expensive plant, you should buy it with the understanding that its maintenance may be difficult.
Aponogeton boivinianus
Yet another plant from Madagascar, Aponogeton biovinianus Has wide heavily puckered leaves that look like a piece of kelly green seersucker. While some sources report that this is one of the more difficult Aponogetons, other people seem to have very good luck with it. What is clear is that this is another plant that requires very clean water as well as a rich substrate. Unfortunately, this plant has not been successfully propagated at this time, so supplies are imported from the wild, with the result that it is on the expensive side.
Aponogeton undulatus
This plant is similar in form to A. crispus, but the leaves are a truer green, (crispus is brownish) and slightly narrower. It comes from India and northern Indo-China. It seldom flowers, but instead produces stalks with adventitious plantlets, similar to those of Echinodorus sp. (Amazon Swords). It may produce between five and ten of these stalks in a season, each one carrying up to twelve baby plants. This is one of the tougher species, and well suited to the beginner as long as it receives adequate light.
As mentioned before, most Aponogetons die back and need a rest period after a certain length of time. Whether this can be done successfully or not is quite variable. Many people opt to use Aponogeton tubers the way a terrestrial gardener uses spring flower bulbs. After the show is over, the bulb is simple dug up and discarded. If you decide you would like to try to rest your Aponogeton and bring it back again, the following method is recommended.

First, the plant must have been well fertilized and growing in a rich substrate. If not, the tuber will not have been able to store enough nutrients to bring the plant back after dormancy. When the plant has died almost completely back, remove it to a covered container full of damp sand. Place the tuber in the sand and store it in a cool location like the basement at a temperature of 60-65F for a period of six to eight weeks. At the end of this time, replant the tuber in the tank, making sure that you have it right side up. If the plant was able to store enough food during its last growth period, it should begin to sprout within a couple of weeks.

Another fun thing about Aponogetons is the ease with which most will flower. For many people this will be the first (and sometimes the only) aquatic plant they will ever flower. The flowers range in color from white to lavender to yellow, and many are sweetly scented. While the flowers are not large or showy, I find them a charming addition to the surface of the tank.

Many Aponogetons are self-fertile. This means that by brushing a cotton swab or paint brush along the flower, you can do the job that insects would do in the wild, and pollinate the plant. Before long, the flower stalk will start to deteriorate, and seeds will form on the flower stalk. When ripe, the seeds will float away from the stalk, and in the wild would be carried away by the current. Within a few days, the seeds germinate, and drop to the bottom, and you will have a crop of baby Aponogetons growing in your tank. It is probably best to remove the flower stalk to another tank before it drops the seeds if you want to try to grow the babies to adulthood. In the average community tank, the seedlings would be hard pressed to get themselves established with fish moving them around and aquarists vacuuming the gravel.

I urge you to try some Aponogetons in your tank. Start with some of the easy hybrids, and I suspect you'll enjoy them enough that before long you'll want to add to your collection!


This article was originally printed in The Daphnian, publication of the Boston Aquarium Society as monthly instalments of my column, ``Sunken Gardens''. BTW, the column was voted ``best column'' in the North East Council of Aquarium Societies in both 1993 and 1994.
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This page was last updated 29 October 1998