The Bromeliad Tree is a strange invention. I started mounting my new Bromeliad collections on various pieces of wood, brick, and tile. This works good but needed a unifying theme. What better than a big dead tree. But I wanted something that I could grow on that wouldn't rot away leaving me to start over every 2 years. Concrete works. However something with a little porosity would serve the plants better. This was my chance to experiment with Hypertufa. Basically a customized mixture of portland cement, peat moss, and my yard sand. This sets nearly as hard as concrete but retains more moisture. So what I ended up creating was an impressionistic version of a dead tree.
I created the main hollow trunk by making two cylinders of fencing. The outer larger cylinder was lined with plastic inside. The inner smaller cylinder was lined with plastic outside. I piled my Hypertufa mix into the shell over several pours. Can't do too much at once or the weight of the mixture will pop through my flimsy mold.
The entire tree was made with only 2 90 pound bags of portland cement and 1 giant block of peat moss. I used yard sand in plentiful supply. 1 part portland cement, 2 parts peat moss, 1 part sand.
I drilled holes into the cast trunk and inserted rebar to hold the limbs. I packed 8 inch lengths of plastic drainage pipe with Hypertufa and threaded them onto my armature. Later the plastic pipe is cut off.
The tree roots were lumps of Hypertufa molded by hand to look like roots.