I have been trying for some time to use aquarium stem plants (e.g., Hygrophila, Alternanthera, Rotala) in ripariums, but I have thus far only had limited success with them. In contrast to most of the rosette plants that I’ve used (e.g., Cryptocoryne, Echinodorus), most stem plants have failed to prosper in my riparium setups, with tendencies to grow very leggy and with poor vigor. The only ones that I have used with much success are a couple of Bacopa, including B. monnieri and another one that I believe to be B. madagascariensis. These develop as attractive floating carpets when grow in hanging planters and draped across trellis rafts, as shown in the following picture:

Bacopa sp. with Trellis Raft and Small Hanging Planter
About a month ago I decided to replant some nice stems with a little more care with the idea of producing some new propagation material. I set them up in a 20-gallon tank with Small Hanging Planters and Nano Trellis Rafts. They have grown in well. I shot the next picture through the open front canopy of the tank.

Riparium Stem Plants
I’m not really using this tank for display right now, so the underwater area looks dingy. I might try to tidy it up for a full-tank shot. Here is the shot above cropped to detail the plants better:

Riparium Stem Plants
I think that this is promising. I only did this in a haphazard way, but it suggest for me the contrasts of color and texture used in Dutch- style planted aquariums. In contrast with most of my previous attempts planting stems in ripariums, with leggy plants tipping over and becoming bogged down in the aquarium water, these hold their shapes well. I think that some of my other problems might have been due to inadequate light. In this case the light fixture, a pretty bright T5 lamp, shines right down on the plants. I have not included any large swordplants or other big specimens to shade the stems. I also took the time to trim a few of the plants to encourage branching and improve their forms.
Here is a shot zoomed in a little more to show the attractive Pilea sp. clump there on the left side. These are planted on a Nano Trellis Raft with their roots suspended directly in the water.

Pilea sp. in Riparium
Try the following plants, I think they will do well for you:
1) Utricalaria gramminafolia
2) Styrogyne sp. (Hygro sp. Porto Vehlo)
3) Hemianthus callichtroides
4) Hemianthus micromoides
5) Mentha aquatica
Ghanzafar,
Hi there. Thanks very much I didn’t think that anybody was listening out there. I need to go back to that post and remove those php tags. Whoops!
Those are very good suggestions. I do actually have a Staurogyne (don’t know which) in there already. It is the bright green plant in the top left corner. It has grown very well and now it’s covered wit flower buds. I did try Mentha aquatica once, but it fizzled. I wonder if Hemianthus would be too fine to cover the trellis rafts(?). There are just a lot of different stems that one could grow like this and I am pleased to see a little more success with this setup. It looks as though the important thing is to have plenty of light shining down and the plants so that they will not grow leggy.
Hey there is a fun aroid in there. A short little Cyrtosperma johnstonii. You can just barely see one leaf in the upper right-hand corner. This plant grows to something like two meters tall, but I am just nursing it along in here for now. It is wild-looking plant with bright pink leaf veination. Here is the description on the Asiatica Nursery catalog page:
http://www.asiaticanursery.com/index.cfm?fuseaction=plants.plantDetail&plant_id=907