I have the Dennerle book "System for Fascinating Aquariums." There is a picture of an aquascape called Crypto-River and a plant that they call Cryptocoryne crispatula var. flaccidifolia as shown in the picture. I don't have a better photo unfortunately. This does not look like other photos I have seen labeled Cryptocoryne crispatula var. flaccidifolia (They all look like very thin balansae). Can anyone make a positive ID or guess?
All the photos I have seen of Cryptocoryne crispatula var. flaccidifolia are of a thin stringy version of balansae. Tropica lists it as the thin form of balansae. The photo I posted looks like a much different species, so I think Dennerle must be mislabelling it.
All the name ambiguity is this hobby is frustrating, especially when you cannot buy any plants locally to see them!