The Aquatic Gardner - November 2003

Horticultural Tankbusters

There are lots of plants that are just way too big for the average and even larger than average home aquarium. But the sneaky ones are the plants that you don't think will get that big, and them BOOM, they take over a tank.

Madagascar Lace Plants are a pretty good example of this. If they're unhappy or in a small tank with not a lot of substrate and perhaps not that much light (which they tolerate admirably well) then you will have a fairly small plant whose leave may only be 8 inches long. But when these plants have a deep substrate rich in organic matter, in a largish tank with good light, then, stand back, you might not believe how big one lousy laceplant can get.

I've had many of these plants over the years in tanks successively larger: 5, 10, 20, 40, 70 gallons and they still fill any tank I put them in and have leaves so large that half the length of the leaves float just below the surface. I cannot begin to imagine how large of a tank you would need so the leaves would NOT congregate floating below the surface. I'm thinking it would need to be a tank on the order of 3 or 4 feet deep and still fairly long and wide.

There is no secret to laceplant cultivation and it's not clear to me why they have a reputation for being difficult. Ok, there is one sort-of secret: they will only thrive in cool water: 65 - 72F being ideal; they'll tolerate higher temperatures but don't expect much from them over 80F. Innes, in his famous work commented that they do well in both acid and alkaline water.

One of the most impressive tanks I've ever seen was in the basement of a Toronto area plant specialist who had a 65 gallon tank used to hold some laceplant bulbs. He had, I think 100 at the beginning and sold most off very quickly ending up with maybe a dozen in there. I'd see this tanks on visits to the city, but only infrequently and I think I saw it a total of 3 times over about 18 months.

It was an utter jungle; thick with fenestrated leaves and rife with plantlets that had formed from seeds from the famous double flower stalk that identifies African Aponogetons. Why I never took a picture of this I don't understand (slaps head, angrily).

Laceplants have been known in aquaria for decades, but in the 1980s a new Aponogeton found its way into fish stores everywhere - Aponogeton boivinianus. This plants looks like ocean kelp with it's emerald green wide bullate leaves. Wide as they may be, they're longer than they are wide. And they get BIG.

George Booth, who does a spectacular job of a) growing plants and b) photographing his tanks progress, has a picture on the web of one of these plants that outgrew a 65 gallon tank by a large margin - its leaves measured in at over 4 feet long.

A recipe for "how to fill any tank completely full of leaves" must simply suggest sticking one of these plants in the gravel and you're done. They are going to fill any tank you put them in (assuming of course you aren't a public aquarium with 5000 gallon tanks in which case you might need two of these plants to fill it).

While there are big plants from all over the world, Africa still reins supreme as the home of the largest number of truly huge plants. The next plant we want to look at is very different from most other aquarium plants in that it has round leaves and they're red, which makes a nice counterpoint to tall thin green leaves; this plant of course is the African Red Tiger Lotus.

This is another plant that is going to get as huge as it has room for - the bigger the tank the bigger it will get and again one or two of these plants are going to fill pretty much any tank you throw at it.

There are other similar plants related to this - there are many different forms and species of aquatic lilies used in aquaria - and these differ from pond lilies in one important way: the water lilies we want for aquaria make leaves IN the water, not leaves that float on the surface like water lilies you see in ponds. These are really not appropriate for aquaria as all they are going to do is make a tank full of stems and out up a large number of far too big floating leaves and that's even if - rather a big if - they get enough light to make them happy. Given they take full sunlight in pond cultivation, a pond water lily is just not going to work out in an aquarium and this is where the Tiger Lotus and related water lilies DO excel - Nymphea stellata comes to mind as well as another water lily that's well suited to large aquaria.

So far all the plants we've discussed have bulbs, but that doesn't mean they reproduce in the same way. Aponogetons reproduce by making flowers which set seeds which make, if you're lucky, lots and lots of tiny plants which will grow up to be big or even huge plants.

Aponogetons can be divided into two basic types: plants that look like A. crispus with it's long narrow strap like green leaves, and "the rest". While there are a few species of Aponogetons that look like crispus - and these are primarily Asian species, it's the African ones that stand out as being rather different. A. madagascariensis and A. boivinianus are just two, the third one I'd like to mention here is A. ulvaceous, which looks like a crispus on steroids. Another huge plant, it's long strap like green leaves are fairly wide, far wider than the one inch or so size the crispus and related plants attain and undulate gently. Ulvaceous, like the two Aponogetons mentioned earlier will also get very large - leaves found inches wide and over a foot or two long are not uncommon, and like laceplants they also set seed on double forked flower spikes.

Sometimes you will get a second plant growing from the bulb of an Aponogeton and in the case where these is a fairly strong growing plant it may become large enough that you can carefully slice the bulb and by separating the two (or more) plants they can be reproduced by bulb division. Note however this is not common nor does it work all the time. You also have a good chance the bulb will just rot and the whole mess will die, but from time to time in the literature you'll see this suggested as a propogation technique and yes, from time to time it does indeed work.

Other than this, you'll have to rely on propogation by seed to reproduce Aponogetons, and while that's not particularly difficult it's nor particularly easy either. Tiny baby Aponogetons are not the most robust plants and are easily disturbed by fish, or destroyed by algae if you're having a problem with that. The 65 gallon tank I mentioned with nothing but laceplants? It had no fish in it.

But take heart, if you really want to reproduce Aponogetons and don't want to hassle the pollination, germination and care of tiny plants then you want Aponogeton stachysporous, at least I think that's what it's called these days - it's name seems to have changed from that to others then back again from what I can tell, but if you say "A. stachysporous" to aquatic plant people they'll know what you means. "oh, the livebearing one".

When A. stachysporous sends up the characteristic Aponogeton flowering stalk you'll notice a difference in the shape of it and that it produces no flowers - instead it produces a small version of itself, complete with bulb, at the end of the flower stalk. You're best to leave it and try to not have any damage occur to the flowering stalk as that would mean the death of this new tiny plant until it's large enough to be separated from it's parent at around 4 inches tall. Usually by then though the flowering stalk has just begun to rot away and the baby plant and bulb is more than ready to grow on it's own. These plants are stupid-easy to reproduce

The aquatic lilies, are similar so A. stachysporous in method of reproduction. They must flower and set seed but this is very rare in aquaria and the usual mode of reproduction is similar to A. stachysprous - sort of.

If you purchase, say, a red tiger lotus, you may or may not get a plant or you may get only a chestnut sized round brown lump of a bulb. This is a good thing as while it's possible to grow these plants without a bulb - don't. While they will grow a new bulb it may take a while - even years before a good sized one is formed. The bulb is everything though, and if you purchase a bulb with just the tiniest of plants growing from it what you'll see is one plant that will just take off and become the dominant growing point - it will make a huge plant but what it does is grow a couple of inches from the bulb, on what appears to be a runner or stolon. When the plant is a good size this stolon can be cut. The plant will grow a new bulb (but again, this may take a while) and the bulb, if it's happy, will put out another plant and this process will repeat and go on as many times as want provided the plants - which replenish the bulbs nutrient supply - have ample light and nutrients. Those bulbs are little plant generating machines.

Both aquatic lilies and Aponogetons are very very heavy feeders and will show a pronounced slow-down in growth when they're a little shy of nutrients. This small tablets of fertilizer placed down into the roots are a tremendous asset if you're interested in these plants. Every couple of months seems to be about right but keep in mind this is when I grew them in a substrate that already had manure under packed fine beach sand to a depth of 4 inches. All these plants are increadably heavy feeders.

Once again I notice I've taken a tangential swipe at the theme of this issue and have squandered it talking about some of my favorite plants, so to get back on theme of things you might not really want to keep in an aquarium: Cape Fear Spatterdock and Banana Plants. The former is really a cool water plant with a large rootstock that is very sensitive to rot. I have not once been successful with this plant and there is nothing on earth that smells as bad as a rotting spatterdock root - I mean nothing. Banana plants, on the other hand are not terribly hard to grow and their root system is different and kinda neat, but have you ever seen a picture of a banana plant with an impressive display of leaves in an aquarium? No, and you won't either. They will put up submersed leaves for a while till they figure out things are safe, then they'll put up floating leaves 100% of the time. So if you want an impressive array of stems in your aquarium then a banana plant is for you. I'll pass though, frankly.