This was originaly a comment I left on Jason Bricks discussion about a fantasy version of Dwarf Trees.The basic premise is, what appears to be a small tree above ground is actually a huge underground tree.
I decided I would post one of my responses here as I find it interesting and wanted to save it, since I will likely use it in later campaigns.
here. Which contains more fun ideas about The Dwarf's Trees.
When dwarf trees ( or The Dwarf's Trees as some people call them) grow in a circle cultivated by fairies, the underground cone of wood that is formed becomes almost completely impenetrable due to their tough nature and the fairy magic.
One of the few ways into an underground fairy circle, which is alot like a tiny city, is to first destroy the magic of the above ground circle of foliage. Which can itself be very difficult. Its like taking on an ant colony of fairy folk.
The above ground circle may appear to be between 7 to 13 trees only 12 to 15 feet tall sometimes even appearing smaller like sprawling bushes of branches. But underneath is a cone of dwarf tree trunks going hundreds of feet down with the trees interlocking making it wider then a human house or even larger.
It is unknown exactly how many fairy folk, gnomes or other of their kin can live inside an underground fairy circle. But it has been seen that over populated fairy cities sometimes hollow out old parts of the trunk and 15 foot thick branches to make room for more fairy residences.
Sometimes the mischief caused by such a fairy city stretches hundreds of miles away from the source.
Some fairy mounds, as the traditional fairy citys are called, is actually a circle of dwarf trees who's branches have been buried over and grass and flowers grown right on top disguising the circle as a knoll or foot hill.
This may be further evidence that dwarf trees may be able to survive without sun light.