At the March general meeting of MAS, we distributed a large number of Aponogeton undulatus bulbs. Because of the interest in the propagation of the plant, I thought it might be interesting to review what is written about the genus.
(only genus in family)
Distribution: Tropical Asia, India, Indonesia, Malaya, Korea, Australia, Madagascar, Tropical Africa
Approximately 50 species are known; the species suitable for the aquarium come mainly from tropical Asia, Indonesia, the Malay peninsula, and Madagascar. Those from Africa are either not amphibious, require an extensive rest period, or are very robust and develop leaves suitable more for ponds than aquariums.
Now to our specific project:
Those species currently available on a regular basis are as follows: Aponogeton crispus, A. bernieranus, A. elongatus, A. madagascariensis, A. natans, A. rigidifolius, A. undulatus, A. ulvaceous,A. loriae, A. henketianus, and A. boivinianus. Other more rare species will be imported from time to time, so check the plant displays carefully.
Aquarium conditions: Most aquarium suited species will tolerate a wide range of water, light, and nutrient levels. In general, the best conditions are good lighting, medium soft to medium hard water, a nutrient rich substrate or a small pot with iron rich media and sand. Do not bury the bulbs. Allow the bulbs to lay on the substrate until they begin to sprout. Then gently push them in, until half buried in a horizontal fashion. If no nutrient rich substrate is used, the bulb will use up all of its own "food" and as it goes into the rest period, the bulb will rot or end up hollowed-out.
Rest Period: With the exception of A. rigidifolius, all Aponogetons need a rest period of one to two months. When the leaves begin to die back, usually in the early fall (midwest USA) remove the plant, and store in clean, barely damp sand in a cool place. Keep in mind that many of the species have been crossed and do not seem to respond to a rest period like those that have been "farmed" with a bit of integrity.
Propagation: In general, it can be stated that all of the species are propagated by sexual means, except A. undulatus, and A. rigidifolius. However, many of the species will develop side shoots or unusually shaped bulbs which can be separated with a sharp knife and so are propagated vegetatively by the aquarist.
Aquarium conditions outlined above fit this species very well. A major Florida importer and grower enriches the "vat" with an iron-rich media and covers it with about two inches of sand. The bulbs are placed on the sand and when sprouted, pressed into the sand slightly. In the aquarium, fine gravel may take the place of sand and will work equally as well provided it has been aged and fertilized. The water temperature plays a major role in faster growth. The optimum temperature seems to be 76°F with variance from 68°F to 82°F. When using sand as the substrate, test it first phosphoric acid. If it foams slightly it should not be used (Lime-away is 9% phosphoric acid). Lighting should be similar to that of any good plant tank; full spectrum lighting, which simulates sunlight and is intense enough so that your hand will cast a dark shadow when placed two or three inches from the bottom. Less light will reduce the rate of growth and the leaves may not be as long or robust. The plant will still grow and reproduce, but more patience will be needed to see results.
A. undulatus sends up a flowering stalk which usually will bear several young corms or bulbs. These can be anchored in the substrate and eventually separated from the adult plant. Much of the literature, states that this plant will grow 10 to 16 inches in height. I have found that with reasonably good conditions, it will reach 24 inches, and I have seen even larger specimens.
Once the young plants begin to grow roots, bend the stalk over without braking it, and secure it in the substrate. At this time, your plant should be verified by a MAS member. Clip the stalk after the young plant appears to be rooted, and sprouting additional leaves. When the new plants have been on their own for four to six weeks, gently remove one from the aquarium, place it in a dampened plastic bag and enter it in the Horticultural Award Program for fifteen HAP points.
I hope your success in this project leads to more enjoyment of the hobby and an increased sense of knowledge and accomplishment.
Aquarium Plants. Rataj/Horeman. 1977.
Aquarium Atlas.. Baensch/Riehl. 1982.
Aquarium Atlas 2. Baensch/Riehl. 1993.
Water Plants in the Aquarium. Scheurmann. 1950.
Aquatic Plants/Aquarium Digest International.