Lysimachia, photo by the author

The Planted Tank

Flowers in the Aquarium

By Robert Paul Hudson


All plants flower as part of reproduction, and aquarium plants are no different. Flowers are formed either when the plant breaks the water surface or a flower stalk grows from the crown of the plant all the way to the water surface.

Plants usually do not flower under water, and if they do it is by accident not by design. Anubias species in the natural world grow in very shallow water with leaves partially or fully exposed. In the aquarium we keep these plants in water too deep for it to reach the water surface and the flower stalk is very short, so sometimes the flower will open for a brief time underwater.

Sword plants, (Echinodorus) lilies, (Nymphaea), Crinums and Aponogetons each send out a long vine like stalk that may reach over two feet to hit the water surface and bloom. Aponogetons have a rather diminutive flower spike consisting of a tiny cluster of flowers at the tip. Echinodorus have small white flowers in multiple clusters all along the stalk as it lies across the water surface. Nymphaea and Crinums have large spectacular flowers. Nymphaea is cultivated for it’s blooms in ponds and has a whole variety of colors and shapes.

Many stem plants have multiple blooms from the sides of the stems at the leaf elbows above water. Cabomba furcata has deep blue flowers while Lysimachia has bright yellow flowers.

Sidebar
Lysimachia is an interesting plant because it grows in and above water, and as a strictly terrestrial plant. It is used as a border-bed plant in gardens, a “cutting” plant in vases, an edge plant in ponds, and for aquascaping the aquarium.

Inducing the bloom

The best way to encourage flowering varies from plant to plant. Light duration is often the key as well as temperature. Some plants in their natural environment flower only in the summer or only in the winter, and some during the entire year. Research would have to be done on each plant to determine if flowers during a short day or a long day. In general you should provide plenty of light and nutrients and C 02. Stem plants such as Bacopa, Ludwigia or Heteranthera should be allowed to grow above the water surface and plants that produce long flower stalks should be well fed and left alone to mature without being constantly moved.

Open top aquariums provide a way of viewing flowering plants. Lights should be suspended about six inches above the tank, or three inches above the tops of any plants above water to prevent the leaves or flowers from being singed. These plants should be placed along the rear and side edges so as to not block light to the other plants below.

I have become interested in creating a planted aquarium and am learning slowly through trial and error. I presently have two tanks, a ten and twenty gallon. In the twenty gallon I have a java fern, which is doing well or at least holding its own, Red Arrowhead which is either disintegrating or being eaten rapidly by the fish, and hedge which is doing well but has a black coating on many if not all of its leaves. the coating can be rubbed off. What do you suspect this might be? If it is an algae what is the best way to combat it? Is there a fish or snail that will eat it? Enough of it to clean up the plants? My next project is a 40 gallon with a better substrate and cable heat. But I need to have a bit of success before I kick that one into gear. Can you help me through this problem with the black on the leaves?

Thank you
Jeff Tobin
Via the internet

Arrowhead and Hedge plants are not true aquatic plants and should be grown in a terrarium only. Many aquarium/pet stores sell both types of plants together and do not understand the difference between them. Plants that are better able to grow under water will be less likely to have algae problems if you are providing enough light and other conditions to keep the plants healthy. Java fern, Anubias, and some Cryptocoryne species are good beginner plants because they are slow growing and do not require intensive light and are very durable. I would start with those plants and then keep your water as clean and fresh as possible doing weekly water changes to keep algae at a minimum and then do some research on the internet about different approaches to keeping a more sophisticated plant tank and what the lighting requirements are. Start simple and then explore how much further you are willing to go. Light, C02, and nutrients are much more important than substrate heaters. There are various algae eating fish and shrimp that will help, but first you need to have the appropriate plants and lighting.

The internet is a great resource for this kind of information. FAMA’s own online database, my WEB site, (www.aquabotanic.com) and online discussion forums, (such as www.aquaticplantcentral.com) provide a wealth of information which will make your hobby much more enjoyable and successful.