[HeyPK]

They should be emersed, or at least in shallow water. There are a few, such as C. pontederiifolia that will even try to bloom underwater, although they don't have any mechanism to get their flower to the surface. Some of the normally submersed crypts, such as C. aponogetifolia, bloom normally submersed and are able to get their flowers to the surface. Daylength is important. Experiment at around 12 to 9 hours of light. My limited experience is that I usually get flowers in the spring or the fall. If all else fails, try small amounts of gibberellic acid. See

Davis, Greg and Mike Kane, Inducing Flowering in Cryptocoryne Species, TAG, V8#5 Sept-Oct 1995

 

[HeyPK]

I had some crypt flowers, but, unfortunately, they collapsed before I was able to get the time to photograph them. The flowers supported my belief that the plants were C. walkeri, based on their long, rather narrow leaves. The flowers were a reddish brown, and the collar was not different in color from the limb, only slightly lighter colored. The throat was more a light red. On Jan Bastmeijer's Crypt pages, there are pictures of C. walkeri flowers ranging from light green to yellow, to brown. Mine was most like the brown one, but the collar in Jan's picture is more distinctly lighter colored, than in my flowers. C. wendtii and C. beckettii flowers mostly have a distinctly darker collar than the limb or throat.

The plants were grown emersed in a covered gallon jar on an east-facing windowsill. they were crowded and looked a bit nitrogen deficient.