This is a huge tree located somewhere in the South Quarter area. Its root system, the only part ever seen in the TDS mission "Into the Pagan Sanctuary", supports a spacious gallery called the Taproot Cave.
The Jacknall's Paw Nestled Inside Root
The tree holds the Jacknall's Paw in a small gash in its giant central root, secured by three branches. The branches disappear, one at a time, with the completion of each stage of the Ritual of the Root. If the ritual is not properly performed, the Paw cannot be removed without killing its possessor.[1]
The ritual consists of three sacrificial offerings to the Heartoak. The "gifts o' the Woodsie", water, moss, and blood, are given to the tree in exchange for the Paw.[2]