This is my plant. I've had it 10y and it only grows when I transplant it into a bigger pot. I don't know what it is but I like it very much because it is very low-maintenance and survives my slack care. And fits on a windowsill. Occasionally it gets a knock and a piece beaks off. I've usually managed to root those pieces and consequently have several sibling plants around the house, all of which are growing straight up.
See those 'hairs' sticking out of the bottom of the U where the stem is bent? If I rest that part on another pot of earth, or on a damp paper towel, will it take root (like a strawberry)? Can I propagate my plant this way, and then cut off the sideways stem so that it can grow straight up and not keep falling over?
It's Crassula ovata - aka Jade tree or Money plant, practically indestructible! It is SO easy to propagate - any small pieces of stem or even a single leaf will root, just by placing it on gritty compost ( it's a succulent, so needs a well drained potting mix) and waiting for small roots to appear - it doesn't even need any water at this stage. When roots do show, just pot up in gritty compost and don't overwater it. So, yes, you could air-layer the stem, but could also just cut it off and root as described above. It might even look better after a bit of pruning!