Plants are essential for an ecosphere to flourish as they serve as the primary producer of the ecosystem and without them the ecosphere would die. They oxygenate the water and filter out chemicals which occur from the decomposition of organic matter such as ammonia, nitrites and nitrates. They also provide food for nearly all the organisms inside. Most aquarium plants work well in ecospheres but here are a selection of the plants that I know can survive the best in ecospheres.
I have noticed that the most successful ecospheres tend to have large amounts of plants so more plants is often better, I would also recommend using at least 2 different plants to add diversity as different plants can fill different niches in your ecosphere.
Diatoms (Bacillariophyceae sp)
Water lettuce (Pistia stratiotes)
Red root floaters (Phyllanthus fluitans)
Java moss (Vesicularia dubyana/Taxiphyllum barbieri)
Indian toothcup (Rotala indica)
Brazilian waterweed (Egeria densa)
American shoreweed (Littorella uniflora)
Eelweed (Vallisneria spriralis)
Hornwort (Ceratophyllum demersum)