Name: Pistia stratiotes
Pistia stratiotes is a popular pond plant that also makes a good indoor aquarium plant. It has attractive thick, green leaves and trailing, elegant roots, which are especially good for set-ups with fry. I have this plant in my 75 liter South American community tank, where it covers the top. The diameter of a typical plant in my tank is 15-20 cm, but outdoors a large specimen can be the size of a small cabbage. The largest individual leaf I have measured is 12 cm, and 14 cm is the reported maximum. No matter how much light they receive, the flowers are inconspicuous, but if you peer straight down into the middle of the plant, you can just see them. Reproduction is from runners, called stolons, which the plant throws out regularly. Snails find the expired stalks very tasty, and line up along the length of them to dine.
My water lettuce thrives in a low pH, low hardness tank with a brisk water current, but these may not be its preferred conditions. Its growing habit is to be crowded and choked and, in the space of 60x30 cm2, I have twelve or thirteen 15-20 cm water lettuce plants, with many more of smaller diameter filling in the spaces between and cramming into the corners. Tank maintenance is awkward, and plant maintenance is fairly high, but easy to do. Expired and yellowing leaves need to be removed regularly, and the stolons need to be taken out (unless you leave them in for the snails, of course!)
It's a responsive and fun plant, and I'd grow it just for the roots, which are tremendously attractive. They grow out in a rosette pattern from the base,
and may reach all the way to the substrate. Water lettuce will shade other plants in the tank, and compete successfully with them for nutrients; so, too, will it deprive algae of nutrients and light, and greatly reduce their numbers, as it did in my aquarium. It has provided my Endler's livebearer fry with food to eat and places to hide from voracious tetras. When it comes to indoor aquarium plants, water lettuce is an oddball, but I like it.
A Miniature Form
Pistia stratiotes will develop a miniature form under certain conditions, as it did, accidentally, in one of my small aquariums. As an experiment (and to get them out of my way) I had placed two medium sized Pistia plants on the water surface of a 10 liter rectangular tank. After a short time, the larger leaves became yellow and translucent. As they were removed, ever smaller leaves came to replace them, getting smaller each time and losing the ridged look of the large leaves. Babies were thrown out on skinnier runners (stolons about the diameter of Anubias roots) until all the plants in the tank were mini-sized. Not one of them was more than 3 cm in diameter, and the individual leaves were 3-6 mm and smaller. My friend Elizabeth Begley took this photo of them in July 2005, when the plants looked their best. After about a year, the miniature plants began to disappear. I thinned the ones that looked bad, and the rest just melted away. I can draw no conclusions, since nature took its course, and I did nothing to help or hinder the process. It was very attractive while it lasted.
I got some of this stuff for my planted tank about one month ago. I had about a zip lock baggie full and I dumped it in right away. What I found is it lets down very little light, but gives a very beautiful look. Because of how it blocked the light, I made a divider out of lego (yes, lego) and I put the Pistia in on the side with little plants and a lot of algae. Not only did it kill the algae, it made the fish extremely happy. It has multiplied like crazy and has grown no bigger than a baseball. That was the biggest I have ever had. I also noticed that some would die that wasn't under the light, so I lowered the water level a little so all the plant would get the light. If you can get this plant, it is really beautiful. Also, small fry seem to love to hide in the roots. Good luck!
I've had my water lettuce for about a year now. I had at first picked it up for free from a pet store owner, and it quickly spread to cover my 110 liter, and then my 280 liter along with duckweed. It was about 8 cm wide and with roots up to 15 cm long. After I got rid of the duckweed and a lot of the lettuce, the remaining plantlets stayed small and smooth and now the tank is almost covered again. Enjoyable if it doesn't cover the tank and filters, and doesn't collect debris in the roots.
Water lettuce, I love the stuff. Very, very attractive both above and below the water line. I've used it as the secondary cover (water lily is a must have, right?) in container gardens outdoors for several years now. Transplant indoors to an aquarium about mid-September (this is Minnesota after all) and it looks just amazing with the root structure. Unfortunately I've had no success overwintering. It does OK for a month or so, dies off completely by January,
Pistia stratiotes or water lettuce is a Class 2 declared weed here in Queensland (Australia) and it is an offence to possess it. There are huge fines for offering it for sale.
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