Next to nothing is known of the Witchwood Tree, whether historically or biologically. For unknown reasons, the tree is now extinct.
The tree is known to have possessed strong magical properties. Its wood, if broken, would magically regrow at a very fast rate.
Witchwood can be used to replace lost body parts, as it fuses to the body upon addition. The host can then control the wood as though it were an actual part of the body. A rare modern example of this can be seen in the pirate 50% Luke, who lost half of his body in an incident at sea.
Witchwood has also been used by the Slayer Masters, who have used it to construct Witchwood icons. This suggests Witchwood is capable of absorbing certain magical forces. These pendants are needed when killing Cave horrors in the Mos Le'Harmless Caves.