Category: Plants

How to keep, grow and propagate plants.

Terrestrial Plants Sold as Aquatics

Every so often, while I’m checking out aquatic plants at the aquarium shops, I run across terrestrial plants being sold as aquatic plants. I have never asked why such plants were being sold as aquatics though I have read somewhere that these plants may last longer than the real aquatic ones. I find this reasoning rather insulting. True, I’ve seen aquatic plants wither and die in my tanks but there is no way I’m about to submerge a Philodendron or a palm tree (no, I’m not kidding, I’ve seen it) in the hopes it will last longer than some more delicate aquatic plant.

So what’s wrong with submerging terrestrial plants? If you think killing plants and sometimes fish is OK then try it and you will be successful. These plants will hold their shape for a while but inevitably they will drown and rot. As they rot they pollute the aquarium, possibly killing fish in the process. Also, the plant may have been sprayed with pesticides while in a green house. Even pyrethrum-based insecticides, which are fairly harmless to us and pets, are deadly to fish.

So, how to spot a terrestrial plant in a tank full of aquatics? Here is where some basic plant knowledge goes a long way. I have a three-step test.


Submerged leaves of truly aquatic plants don’t have a coating that protects them from dehydration. These leaves are thinner and have a lighter, more delicate look than aerial leaves. They are often translucent and hairless. These leaves absorb nutrients from the water much as the roots of terrestrial plants. Aquatic leaves may also have air pockets to stay afloat. But thick, opaque leaves (usually with rotting edges) usually indicate a terrestrial plant.


Fully aquatic plants don’t have to support their weight. Their stems are soft in order to bend with currents and may contain air pockets to help the plant float. Try picking up the plant and holding it out of the water. Plants that spend their whole lives submerged won’t hold their shape.

Bog plants and marginal plants will hold their shape quite well. That’s because they have to deal with fluctuating water levels. Many bog plants (e.g. Amazon swords, crypts, Java fern) will survive fully submerged though they will do better if allowed to send aerial leaves. Unfortunately these aerial leaves usually dry out in our climate or get burned by the aquarium lights. Keep in mind that aerial leaves usually fail step 1.

Marginal plants (e.g. cattails, rushes, irises) usually die if fully submerged. Their leaves are truly aerial, but the plant just adapted itself to live with its roots submerged.


Does the plant remind you of a plant your grandmother had? Have you seen something like it in a garden center? If the answer is yes, you can be 95% sure it is a terrestrial plant. At best it would be a marginal plant. Don’t put it in your aquarium.


All of the above tests rely on generalities. When one looks closely exceptions always come up. Some plants are truly amphibian and do well in either a warm and very humid environment, or fully submerged. Java moss, Java fern, and Anubias are good examples. Other members of the Java fern family (Polypodiaceae) are terrestrial ferns. Likewise the genus Anubias belongs to the family Araceae along with many familiar houseplants (Philodendron, arum, Anthurium, and Dieffenbachia) as well as aquarium plants (Cryptocoryne and water lettuce).

With time and experience one learns to identify the exceptions. When I friend of mine showed me his new Anubias barteri var. nana four years ago, I told him it would be dead in a couple of weeks because it was a terrestrial plant. After all it even failed the grandma test! Well, he was quite proud of himself when he showed me a large patch of it in his tank two years ago. He even game me a clipping. That clipping has grown fivefold fully submerged in my large tank and recently bloomed twice.

Another fellow club member has a less fortunate story to tell. He bought a variegated plant at a reputable store. I don’t know what it was but it was obvious to me it was a terrestrial plant. He suspected it too. The results were some dead and some blinded angelfish. Either the plant had pesticide residue on it, or it released its own toxins in the water.

The next time you see a rather unusual “aquatic” plant for sale put it through the three tests. If it fails, not all is lost. You can put it by itself in a quarantine tank and observe it. If it doesn’t begin to rot and starts growing you may have one of the exceptions. If it starts to rot, take it out of the water and see what happens. You may get a nice houseplant!


Bailey, Liberty Hyde and Bailey, Ethel Zoe (1976). Hortus Third. New York: MacMillan Publishing Company.

Scheurmann, Ines. (1985). The New Aquarium Handbook. Woodbury, NY: Barron’s Educational Series Inc. ?

Stupid Fish Tricks

In the last HAPpenings I mentioned I had done some research on Vallisneria, and I closed by saying that things were getting interesting. Well, read on to see what I found out. First, though, I would like to thank Anne Savannah for getting this whole thing started and lending me her plant bible. Thanks also to Bill Maher, our newest HAP participant, for calling me on the Thanksgiving Weekend and showing me a female Vallisneria americana in bloom. Luckily for the Blooming Competition contestants, Bill did not enter in the competition, so the race is still on. Congratulations Bill, Vallisneria blooms are not common in aquaria around here.

So what is a Vallisneria? According to Hortus Third it is a genus belonging to the family Hydrocharitaceae*. It contains eight to ten species of submersed, dioecious (having separate sexes), grasslike aquatic herbs native to tropical and temperate regions. The leaves are ribbon like. The male flowers are contained “in a head subtended by an ovoid 3-valved spathe on a short scape”. This head looks like the tip of a new runner but larger, transparent, and filled with white dots (see page 53 of the Baensch Aquarium Atlas, Volume 2). The female flowers are “solitary and sessile in a tubular spathe on a long scape coiled or spiraling in fruit”. Imagine a zucchini only a couple of millimeters wide and 20 mm long, with a small flower with triangular petals at one end and a spring at the other end attaching it to the plant. See pictures in the Tropica catalogues (either the official one or the T.F.H. books). The coiled scape is what actually gave Vallisneria spiralis its name, not the twisted leaves as one might think.

The female flowers reach the surface while attached to the plant. The male flowers, on the other hand, detach from the plant when they are ripe and then float to the surface. Surface tension and currents bring two, or more, flowers together and pollination takes place. Once fertilized the female flower is drawn under the surface by the coiling scape and develops a fruit with many seeds.

Thanks to various wild forms, cultivars, and hybridizations (why is it considered OK to hybridize plants anyway?) it is difficult to identify, or even agree on, all the different species of Vallisneria. From all my reference material I managed to identify only five separate species and the descriptions follow. By the way, the surest way of differentiating Vallisneria from the grass-like species of Sagittaria is to check the leaf tips. They are serrated in Vallisneria and smooth in Sagittaria.

Vallisneria americana Michaux, 1803.


V. asiatica var. biwaensis MIKI, 1934.

V. gigantea GRAEBNER, 1912.

V. natans var. biwaensis.

V. spiralis forma tortifolia WENDT, 1952.

V. torta WENDT.

From Atlantic Canada, United States, Caribbean and South East Asia this is the most varied species. It can have straight or twisted leaves and vary considerably in size depending on the variety and the water conditions. Outside fish keeping circles it is known by many common names such as eelgrass, wild celery, and water celery.

The original V. americana has leaves up to 183 cm long and 1.9 cm wide and may show red leaf nervations. The male spathe is 1.6 cm long with three sepals. Female flowers have three petals and three sepals. Supposedly this plant stops growing in Winter even in aquaria. V. americana var. biwaensis, from Lake Biwa in Japan, has twisted leaves.

V. americana (gigantea), the jungle val, has leaves up to 91 cm long and 1.9 cm wide, with five to nine veins with longitudinal black and brown stripes. Female flowers are 2 to 3 cm long and the fruit is up to 20 cm long.

Vallisneria asiatica MIKI, 1934.

From Vietnam, Japan, and Taiwan. According to the Baensch Aquarium Atlas this species is widely cultured in aquaria and it has almost completely displaced V. spiralis, although the aquarium strain is usually identified as V. spiralis.

Leaves can reach 60 cm in length and about 1 cm in width, are not twisted though young leaves show some twisting. The male flowers have 1 stamen, actually a characteristic of V. americana. Female flowers have a 2 cm spathe, with petals 3-4 mm long and 3 reduced stamens. The fruit is up to 20 cm in length.

Vallisneria gracilis F. M. Bailey, 1889.

From Australia. Leaves are straight, up to 40 cm long and 4 mm wide. The male inflorescence reaches up to 4 mm in diameter. This is a much smaller plant in the wild, where it occurs in cool, nutrient poor waters.

Vallisneria neotropicalis Marie Victorin, 1943.

From Southern United States and Cuba, this is a large reddish species and may be the one referred to as V. rubra in some works. In the wild the leaves only reach about 35 cm in length and are blackish red. In aquaria the leaves are longer, up to 150 cm, with a width of up to 2.5 cm, deep green to reddish with dark red stripes running crosswise. There are five veins in each leaf, with the center one being thicker. The male flowers have three stamens. Female flowers have 4 to 4.5 mm long sepals and 1mm long petals.

Vallisneria spiralis LINNÉ, 1753.


V. spiralis forma portugalensis

V. spiralis forma nana

V. spiralis forma pusilla

V. spiralis forma gracilis

Originally from southern Europe but now introduced to many tropical and subtropical regions of the world. This species is known in the trade as Italian val and Tropica markets a variety with reddish stripes as the Tiger Vallisneria.

The leaves reach 60 cm in length and 4 to 7 mm in width, often twisting. Male flowers have two stamens. Female flowers are 1.5 cm long, have three stigmas and are attached to the plant via a spiraling scape.

Cultivation Requirements

Vals are easy to grow and once established they can easily take over a tank. They propagate vegetatively by runners. From the references and from personal experience, these plants do well in brightly-lit tanks, are fine in hard and alkaline water, and benefit from the addition of iron-based fertilizers. I find iron is the limiting factor for Vallisneria in my tanks. Regular iron fertilization results in faster, denser, growth and increases leaf width.

In nature Vallisneria are found in both running and still waters. The ribbon-shaped leaves move in the direction of the current for maximum exposure to light. Their fast growth makes them great oxygenators and nutrient removers in our aquaria. They are also very adaptable to their surroundings. For example the longest vals I had in a 50-L tank (less than 20 cm in depth) barely reached the surface. The same plants in a 50 cm deep and 150 cm long tank grew to be 80 cm long and doubled their leaf width. This versatility make them welcome additions to our aquaria.

That’s it for this month. Before I leave you though I have a trivia question: what Vallisneria isn’t a plant? The answer is on page 13 of this magazine. Hint: it isn’t a plastic Vallisneria.

*The frogbits, genera Hydrocharis and Limnobium, are also in the same family.


Riehl, Rüdiger, and Baensch, Hans A. (1986). Aquarium Atlas. Melle, Germany: MERGUS-Verlag.

Riehl, Rüdiger, and Baensch, Hans A. (1993). Aquarium Atlas Volume 2. Melle, Germany: MERGUS-Verlag.

Bailey, Liberty Hyde and Bailey, Ethel Zoe (1976). Hortus Third. New York: MacMillan Publishing Company.

Stodola, Jiri (1967). Encyclopedia of Aquarium Plants. Neptune City, New Jersey: T.F.H. Publications, Inc.

Stodola, Jiri (1987). Windeløv’s Tropica Catalogue, Aquarium Plants. Neptune City, New Jersey: T.F.H. Publications, Inc.

Tropica Aquarium Plants

. Egå, Denmark: Tropica Aquarium Plants ?

Home Brew

Of all the strange things that I have done over the years for the aquarium hobby the strangest is probably setting up a “home brew” CO2 reactor. Think about it. I am employing yeast to ferment carbohydrates, not, as any sensible human being would do, to create a mood-altering beverage, but instead, to feed carbon dioxide to a glass box filled with water. This is not the sort of thing one can easily explain to casual visitors to your home.

But this is not the first time I’ve done this. I briefly had a yeast-filled pop bottle feeding a 30-liter gourami tank when I was living overseas. It worked…I think. At least the plants grew so quickly they filled the tank in no time flat. But the water coming out of a Hobart tap is some of the purest in the world: naturally soft with a pH of 6.0 or so. So it was hard to know what effect the very small amount of CO2 I injected had had, and what was the effect of using soft acidic water in the first place.

When setting up the gourami tank, my then-future wife, who I had recently met in Hobart, accompanied me on a trip one day to an excellent aquarium store south of the town. They had a lovely show-quality pair of Peruvian severums (Heros appendiculatus). So now severums are her favorite fish, and if you saw this pair you would understand why.

So…when we moved to Calgary she wanted me to get her some severums in payment for putting up with the large aquarium in our living room.

But Calgary’s water, with a hardness of about 150 PPM CaC03, and a pH of 8.0 or so, is not that good when it comes to growing either severums or the vast majority of tropical aquatic plants. They come from water like that magic elixir that flowed from my faucet in Hobart, not that stuff that the limestone-laden Rockies keeps sending down the Bow River.

So I thought I would to try CO2 injection once again, this time to lower the pH for the severums and to provide the plants with a carbon source

I bought a couple of plastic wine carboys at a garage sale. Plastic carboys have proven unsatisfactory for wine making, and so most home wine makers now use glass. You can therefore pick the plastic ones up cheap at garage sales. And one-hole rubber stoppers that fit these things are available everywhere wine making supplies are sold.

Into the carboy went a few seconds of pouring worth of sugar, about 20 liters of warm water, and a healthy dollop of yeast. A length of rigid tubing was stuck through the rubber stopper, and a length of air hose was attached to that. The rubber stopper was put into the carboy’s neck, and the free end of the air hose was stuck up the inlet siphon of the Fluval 303 that filtered the tank. The idea, taken from the Internet, would be that the canister filter would serve as a “CO2 reactor”, with its impeller breaking up the gas bubbles so they would dissolve better.

The tank was already heavily planted with Vallisneria spiralis, Cryptocoryne affinis, Ludwigia repens, Echinodorus bleheri, and Pistia stratiotes. But the tank had no other filtration besides the Fluval 303. And I had placed the outlet hose of the filter below the water line so as to avoid losing the CO2 by surface agitation, as I read you should.

Big mistake!

This first experiment almost ended in complete disaster, as when I got home from work the next day, all five of the young severums looked, for all the world, dead. Their gill covers were stiff and distended, and they were lying on their sides. But there was still some sign of breathing. I yanked the CO2 line from the Fluval’s intake siphon, got an air pump, and had two air-stones running in the tank immediately. Then I did a pH test…the indicator solution’s color was solid yellow, so the pH (whatever it was) had dropped below 5.5 from its original value of 8.2.

This was obviously too effective!

But miraculously, all the fish survived! By the next morning they all seemed happy as clams. The pH by that time had read about neutral.

After the initial near disaster I have worked out a system that seems to work well, keeping the pH neutral or slightly acidic. I took an old Penquin Biowheel out of the closet. It had been relegated to the junk closet because the water pump it came with could not pump enough water (even without any filter media in it) to keep its biowheel turning, rendering the filter useless. This was my first purchase of a Penquin product, and it is so poorly designed (i.e. non-functional) that I have serious doubts about the quality of all other Penquin products as well; so much so that I won’t bother to buy another. But the water pump of the Fluval 303 is considerably stronger than the Penn Plax’s, and so I thought it could turn the wheel. It worked! I stuck the outlet hose of the Fluval into the hole for the siphon tube for the Penquin. The water then flowed back into the tank under the turning biowheel. I have just enough CO2 loss through this system to keep the pH in the safe range, provided that I don’t add too much yeast. Every two weeks I drain ¾ of the water from the carboy and replace it with fresh warm water and a good handful of sugar. This keeps the CO2 bubbling at just the right rate.

The plant growth is very good in all species except the sword plants. I attribute this, with no evidence whatsoever, to a lack of nutrients in the sand (Sil 7) substrate. The books say that sword plants need a nutrient and iron rich substrate.

Remember the “big tank” in the living room whose (admittedly obtrusive) existence led to getting the severums in the first place? Well, this tank held at the time a mixed collection of Lake Malawi cichlids along with some Vallisneria spiralis, Cryptocoryne affinis, and Pistia stratiotes. The tank’s plant filter also had a solid growth of temple plants (Nomaphila stricta). All the plants were doing OK, but the only ones that were actually thriving (in the same way that the plants in the severum tank were thriving) were the temple plants and the water lettuce. But both of these plants grow up out of the water, and so can get their CO2 from the air.

This led me to think that the growth of the fully submerged plants in the Lake Malawi tank was CO2 limited. But CO2 injection is out of the question in a Lake Malawi cichlid tank. These fish are very sensitive to pH changes and need it at a constant 8.2.

However I had grown a little tired of my Lake Malawi cichlids. They are beautiful, yes, but they are also remarkably stupid for cichlids. Where are the great personalities that cichlids are famous for? Not in Rift Lake cichlids in any event. And breeding them was hardly a challenge anymore.

I was ready for new challenges. To try and finally grow healthy, dark-leaved, and flowering sword plants seemed to be what I needed.

So the September auction saw the sale of all my Lake Malawi cichlids. The tank’s gravel substrate was replaced with Sil 9 gravel to which laterite (purchased at Pisces) was added to the lower third. The Lake Malawi rockwork was replaced with some driftwood. And the carboy was set up to inject CO2 into the tank overflow. Yes, it would be great to have a high-pressure CO2 system with an electronic dosimeter, but financial realities are what they are.

The tank’s Vallisneria spiralis and Cryptocoryne affinis were replanted in the new substrate along with some new sword plants from Twyla and the Java fern, Anubias, and Ludwigia from the smaller tank.

Then the severums were moved in (they were getting too big for their 125-liter tank anyway) along with a small army of Otocinclus affinis from Pisces and a large school of Corydoras gossei and Corydoras baineno from Birgit.

And already I have my first sword plant flower! Plant growth is good, algae growth is getting under control, and the fish are doing well. There are no signs of the fish breeding yet but they are still young. Clearly, the brew has helped!?