That's very interesting to me.
From the hundreds of plants we have transplanted or seen growing in our backyards I have never seen a flower. Also, maybe due to the fact that its "summer" all year long around here, our plants have never gone dormant or appear to die back to the ground. They basically look the same.
Maybe these are all indications of the bad soil (incorrect soil) in which they live.
Naively, I thought I was the only one in the area with this kind of plant because I have never seen one anywhere else, even when I went to Thailand myself. Therefore, I HAVE to go check that plant on the picture you sent me, which is no more than 15 minutes from my home.
I will post back with my findings, and maybe I get a chance to talk to the gardener at Vizcaya, which I have visited every time when someone comes to visit ...but never noticed the huge plant at the entrance.
So is it a type of agave?
Again, many thanks.