Knotted Heartwood

Knotted Heartwood is a wood tradeskill material and is used by architects.

Source
Knotted Heartwood is obtained through salvaging and the survivalist tradeskill and can be found in Algoroc, Celestion, Deradune, and Ellevar. This wood can also be obtained from a Tier 1 Thicket.

Schematics
Knotted Heartwood is used in the following architect schematics: