Cost: -30 points
A variation of No Legs for magic items built as characters
https://web.archive.org/web/20180122213945/http://forums.sjgames.com/showthread.php?t=2711 Bardolph estimated it at -35 in 2004.
In 2008 GURPS Thaumatology pg 119 priced it at -30.
Probably a more realistic tank than Sessile which assumes something absolutely can't be moved, but even a 100ft tree can still be uprooted.
Anchored is taken as a Warp limitation term, but something along those lines could maybe be used to represent uprooting trees.