I get them growing on the side of stumps that were box elder trees beside the house. We cut the trees because we get bad ice storms in winter. Not every winter, but often enough to cause alot of damage to tree limbs on the box elder. I concur that these things grow fast, even up here in the north. A couple weeks and they can be the size that Tom posted. Lately we've had alot of humidty, I think summer finally arived.
There was this lady in town with two huge Carolina poplars (40 plus inches dbh) and she was concerned about them breaking off limbs or the main stem. Actually, the neighbors were more concerned. Well one tree of the two had a shelf fungus on the side coming from a severe scar that looked deep. I told her it would be a good idea to take care of them as soon as possible. In summer we often get freak wind storms out of the North west or North east. Well, I warned her of the possibility for some damage. Well a couple or 3 weeks went bye and there was one of those storms. The one tree that had the bad scar snapped off like a tooth pick and the other was ripped out of the ground, root ball and all. Good thing the trees both fell out over the road, cause there woulda been 2 demolished roofs. Green poplar is DanG heavy stuff.
cheers
