What's going on when roots turn green and grow into the air?
I found this article online that does describes hibiscus plants as having a "spreading" type root system that will also form new shoots away from the parent plant ... http://homeguides.sfgate.com/type-root-hibiscus-have-49085.html

I also noticed that you have an attached orchid with aerial roots attached to the hibiscus plant.  If you are misting the orchid roots periodically, you may be dampening the surface soil in the pot and encouraging the growth of shoot forming spreading roots on the hibiscus plant to develop and grow upward.