A fairy tree is a magical tree that has been grown by and taken care of by the fay folk for various magical purposes.
Fairy trees can be made of any type of tree, are usually the biggest and oldest living trees in a forest, and can be easily recognized at a distance by the presence of many fairy lights (shrunken, glowing fairies, cait sith, and cu sith, as well as any hybrids and demimyths of the species) around it. It usually has an unusually thick trunk, with widespread branches, and a hollow in the trunk near the top, which is used in a fairy ritual to make fairy dust. Also, the fruits grown on this tree look like mundane version of their species, but tend to glow various colors, and are used by the fairies to craft fairy dust.
When a fairy dust user wants to craft said dust, one must gather the right ingredients, mix them in the right way, then pour them into the top of the fairy tree. When that happens, the magic of the tree turns the mixture into a beautiful golden dust that pours out of magical tunnels/spouts grown in the tree, and are gathered and distributed to the users. Also, the magical fruit have the odd property that if one who is not the fay folk eats one, they will forevermore only be able to eat fairy fruit.