Durned if I know. This is what is so frustrating about limited experience. We tend to generalize based on limited successes and failures, and this is not always optimal. Now, I have grown U. longifolia many times. In my experience, when the plant has a large area it can colonize, it does so with abandon. I have never had flowering when the plant was in this type of rapid growth. From this, I conclude that some stress factor is what initiates the flowering process. I picture the plant in habitat spreading as it will, until the stolons encounter some obstruction. Then, they begin to compact, and the sub-surface stolons are forced towards the surface. I *speculate* that this might provide the trigger. The 2 times it has flowered for me in the past have always seen cooler temperatures associated with the short days of winter, so I also conclude that this might also have to do with the initiation of flowers. Sounds reasonable, doesn't it?
Then I heard from a grower in Australia who grows his plants outdoors in a garden bog. No restrictions there to the stolons spreading where they will! He says his plants flower best in warm conditions as the daylength increases. Go figure.
I think Dodec flowered the plants once when they had very short "leaf stolons" (we really need a better term for these, like lollons, leaflons or something!) and I doubt the rootlons
were much compacted. Am I right with this Dodec?
Dodec always says "flowering is more related to photoperiod and temperature"...others say it's the compaction and substrate dryness....
I stick to my theory: These plants flower when the invisible fairies come by with their wands and touch them. They do this whenever there is a big party going on and they need a supply of aprons and skirts. I challenge anyone to prove me wrong!