Originally Posted by MoneyMitch
just curious, as far as wisteria and water sprite go if left untrimmed will these grow to a unlimited height? or do they have a maximum they reach? what happens when they reach that maximum height do they bush out or put runners off like crazy.
You have mentioned two very different forms of plant, so let's first separate.
Wisteria is a stem plant. All stem plants will continue to grow if not affected by something. Wisteria for instance, if a stem is stuck in the substrate, will grow toward the light at the surface, and if left alone will then grow along the surface or into the air, towards the light. This is why we can control stem plants by continually trimming the upper portions of the stem and replanting. It is the same stem after all, just being shortened by us periodically. When allowed to continue unaffected, the lower portions generally lose leaves, since the plant is inherently wanting to grow (photosynthesis, which produces its energy food) and the leaves at the tip will naturally be close to the light and more productive. To my knowledge--but I stand to be corrected by a botanist--stem plants have no maximum length; the length is determined by those external forces like light, surface, tank lid, available nutrients, etc.
Water Sprite is not a stem plant but one having a crown from which the leaves and roots emerge. I'm sure there is a botanical name for these, but it escapes me. In these plants, the leaves do tend to grow to a maximum length, but I've no idea what this might be for the fern Ceratopteris. I have had them extend across the aquarium surface to a distance of close to 18-20 inches (each frond or leaf).