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Issue: October 2007

Vallisneria

Author: Rhonda Wilson


Photographer: Rhonda Wilson
The Planted Tank: October 2007

Vallisneria is the truly classic aquarium plant. A tall rosette-type plant, it’s easily propagated and is one of the earliest plants used in the aquarium hobby—and it’s still one of the most common and easiest to grow. A member of the Hydrocharitaceae family, Vallisneria is related to several other common aquatic plants, including anacharis, frogbit, Najas, and Blyxa.

Vallisneria is often one of the first plants aquarists will attempt to grow, and it will usually be very successful. It is a truly aquatic plant, as it will not create leaves that can live in an emerged state and it will not survive long if it’s taken out of water. Despite the fact that the plant is distributed worldwide, is very common, has long been known, and is easy to grow. It’s also a rather interesting and mysterious plant scientifically.

Some species of Sagittaria, and perhaps the pygmy chain sword Echinodorus tenellus, can sometimes be confused with the Vallisneria plants. I have found that Sagittaria is usually thicker leaved and often shorter (though not always). If you look very closely at the tips of the leaves you can often see tiny spikes on the Vallisneria, like little teeth along the edge, whereas Sagittaria leaves have smooth edges.

Naming your Vallisneria

The most difficult aspect of dealing with Vallisneria is the names of the plants themselves. Vallisneria will grow very differently in various conditions. This makes it hard for scientists to determine whether they are looking at a new variety of the same plant, or a new plant altogether. If trained scientists have trouble deciding what type of Vallisneria they have, then how are the rest of us supposed to figure it out? Trying to judge what type of Vallisneria I’ve grown has certainly been something I’ve had trouble with. Not only are there different scientific names for these plants, but common ones too.

Because these plants are so variable, scientists have turned to the flowers to identify which plants belong to which species. For most of the world the plants have been grouped into two species, V. americana and V. spiralis. V. americana includes the large Vallisneria often called jungle val; the twisted types, including biwaensis and some of the americana, have the more typical val ribbon leaf shape. These plants originate in the Americas and Asia.

You may have noticed I said that for most of the world, the plants have been grouped into two species. Recently another Vallisneria plant, V. nana, has come into the hobby. These are from Australia, and they aren’t the only plants of this genus there. It looks as though there are several species of Vallisneria in Australia. Hopefully we’ll be seeing more of them in the hobby in the near future.  

Vallisneria in the Aquarium

In the aquarium Vallisneria are generally very easy to grow—as long as you don’t try to keep them in too soft or acidic water. I’ve never lived in an area with unusually soft water so I can’t speak from experience, but the genus is consistently listed as coming from areas with hard alkaline conditions, and it is usually mentioned in other resources that it doesn’t do well in soft water. In fact some Vallisneria will even tolerate low levels of salinity and can be used in a slightly brackish aquarium.

Vallisneria has always grown incredibly well for me. The plainer, straight-leaved plants have been the easiest to grow. These can be V. americana or spiralis. The plants grow so well they are often more like weeds, requiring a lot of regular pruning. The leaves can be trimmed with scissors to the length you prefer, to keep them from covering the top of the tank, or you can leave them so as to provide shade or hiding places for smaller fish or fry.

You can grow the taller Vallisneria in the background, but I can’t say enough that you will have to keep them in control or they will take over the tank. Because of their size I’ve found the high Vallisneria plants are best displayed in tall tanks. Extra high tanks and tall hex tanks are often hard to plant, but Vallisneria are the perfect plants for these tanks, and with their rapid growth it’s really easiest to just let them take over most of the tank. A lower-growing low-light plant or two in the front, like Cryptocoryneor a moss, can make a nice planted aquarium out of an otherwise difficult-to-plant tank. A tall piece of wood or a few rocks can complement the look as well.

The largest of the Vallisneria is often called the jungle val. These plants have been classified as V. americana also, but they require different housing than the smaller plants. These plants usually have much wider and thicker leaves and can grow very long. The leaves can easily grow to 6 feet in length and longer. In a smaller or shorter tank those leaves will very quickly smother out all the light from anything below it. As the plants get more crowded they will push leaves out of the water that will dry out and die, making an unsightly mess of your tank. The Jungle val is a beautiful plant when kept in a very tall tank appropriate for its size and growth.

Twisted-leaved Vallisneria have been a bit shorter and less invasive for me than the straight-leaved plants, but the twisted-leaved plants have had better growth for me in tanks with added CO2. I know other people that have also had very good results with this plant in tanks with CO2 and added nutrients. The twisted leaves can be very impressive looking, and the shorter height makes these plants better for mixing with other plants and more suitable to a structured aquarium than some of the other harder-to-control Vallisneria.

Vallisneria nana has a much more narrow leaf. It’s recently become available to hobbyists in the United States. These Australian plants were originally described as Physkium natans in 1790. I was given a start from one of these plants and added it to an aquarium with CO2 injection. The V. natans has mostly been covered and engulfed by the stemmed plants in that tank. It seems to take a while for this val to get established, but I notice that it has been sending out runners and its long leaves are starting to poke out between some of the other plants. That said, I think this plant looks nicest in large group plantings, and after mine grow out more I will move them to a more appropriate tank.

Planting and Propagation

Planting your Vallisneria couldn’t be easier. The plant’s roots should be placed under the substrate, and the crown where the leaves grow out should be just above the substrate. Careful gardeners like to use long tweezers for planting, but I prefer my fingers. Depending on the tank and what’s in it, I usually plug the plant into the substrate then pull just enough out so only the roots are underground. Or, if there is more room, I use a sweeping motion through the substrate, bringing the plant in a bit off of where I want it to finally sit. Then I sweep the roots through the gravel, bringing the plant to the desired location. The roots stay under the substrate to the side of the plant.

The most common form of propagation for Vallisneria is through runners. These will grow all over the aquarium and each new plant will quickly start sending out runners of its own. They can very quickly take over the entire tank this way. An important part of growing Vallisneria is controlling it. The runners can be pulled out and pinched or clipped off the main plant and either planted elsewhere or disposed of responsibly.

You can try to contain the runners using pots or other barriers. I’ve tried this myself but didn’t find it at all effective, as the runners just go up over the edge of the pot and continue on their merry way, growing across the rest of the tank.

Flowering and Seed Production

One of the more interesting aspects of Vallisneria plants is something that isn’t seen often in the aquarium, and that’s their flowering and seed production. Vallisneria produce both male and female plants. The female plants produce flowers that float on the water surface, and the male plants produce hundreds of flowers under water that, when released, float to the surface. These are carried by wind and waves to the floating female flowers, which they pollinate. After pollination the female plant produces the seeds.

Vallisneria is a great beginner’s plant, a fast grower, and comes in a variety of leaf sizes, some with lovely twists. Its tall graceful ribbon-like leaves have graced aquariums for many years, and these easy-to-grow plants have a truly well-earned reputation as an aquarium classic.



See the full article on TFH Digital http://www.tfhdigital.com/tfh/200710/#pg56

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