An orchid in an aquarium?? Sounds a bit unbelievable, doesn’t it? Well , it can be done. While it may be hard to find a dealer selling a water orchid these days, a bit of sleuthing should turn up a source. The water orchid is indeed an actual orchid. While the older literature lists them as Spiranthes lancifolia, the ones that I obtained years ago were in actuality either Spiranthes cernua or Spiranthes odorata. The genus Spiranthes is one of terrestrial plants, some of which do live in areas that are swampy and may be submerged at times.
Those that have been sold as aquarium plants are of the latter type. They will live submerged and will grow, however, they will likely never bloom. If a bloom is desired, the plant will need to be grown emersed in a pot. The planting medium can be sphagnum moss , with or without added materials (bark , perlite, etc.). Do not allow the medium to dry out. When I had them, they did fine under lights in my fishroom and bloomed regularly.
Plants in the genus Spiranthes all have sword shaped leaves (oblong lanceolate). The roots are husky and whitish in color. Most are fairly small in stature. The species sold as water orchids (cernua, odorata) are not that small. The mature plant without inflorescence can be up to a foot tall. The inflorescence arises from the center of the rosette and will bring the height to 30 inches or so. The tubular flowers are a light celery green to white and spiral up the inflorescence (the genus name means spiral flower). The spiral effect is not readily seen unless one looks down on the inflorescence from the top. In the case of Spiranthes odorata, the flowers are slightly fragrant. If you are looking for a true oddity for your aquarium or indoor pond, try searching out a water orchid. You won’t be disappointed.