Cavewood trees grow exclusively in Exile and make up most of the trees found in the caves. Magically engineered by Erika Redmark to grow in stone, these trees can take root in almost any surface. Their leaves were designed to rely more on moisture, plentiful below ground, and less on light. These modifications were made possible by altering the substance of the trees. Cavewood trees are actually an amalgam of cavewood and fungus.
For the difficulty in creating and the effort involved in maintaining them, their wood was a scarce material throughout Avernum; most buildings were constructed from stone with only the doors being made from wood (if they were not simply open archways). Cavewood can also be worked into bows, but the resulting weapon does not have much firing power or accuracy. It is interesting to note that the Vahnatai have their own form of cavewood trees that are native to their lands.
Now that trade lines have been opened from the surface to the caves, the use of surface woods in Avernite construction has increased, but cavewood is still the most common lumber, despite the fact that it is almost exclusively used for fences.