Here's a pic of my Allagoptera in 2009:
in 2010:
and the one I took last week:
So, yeah, I'd say it is a pretty slow grower. I originally got it to put on the deck of our beach place, right on the water with lots of salt air. However, I really liked it and I can't guarantee that it would get regularly watered plus we get more hurricanes over there and I didn't want the maid to have to try and haul it inside if one were coming. Anyway, I kept it here in the city and I'm really happy I did.
It says that the trunk is usually buried in the soil but I can see a small bit of mine as it gets taller. It leans towards the sun and the pool which I really like.
I found a picture of the tag when I was searching for old pics of it, I paid $325 pesos for it. I don't remember the exchange rate then but it would be between $25 and $30us.
