The Wykem-Tree is a very rare tree that grows in areas where many people have died and their bodies have been left undisturbed for decades. As the tree matures it produces thin stalks along it's trunk which can be harvested for their potent sap which has curative properties.
The older the tree, the more potent the sap found in these stalks. The only known Wykem Trees left are jealously guarded by Fey, for their rumoured connection to the tree's wooden stalks.