From Ryzom Wiki
Root is an affliction; a negative status effect that handicaps the target.
Not be confused with Rot, an elemental damage type.
A creature under the effect of Root is unable to move while they are rooted, though they can still take any other action. Thus it's particularly useful against enemies who only have melee attacks.
Root as spell
Players are able to inflict Root on a target using the Root spell from the Offensive Affliction Magic skill. This spell is first available at level 10 magic. Like with all affliction spells, a link must be maintained to keep the target rooted.
Players can increase their chances of resisting a Root Affliction spell by wearing jewelry that raises their Jungle resistance.
Enemies using Root
Since homin mages are capable of casting Root affliction spells, it may be used against you in PvP. It may also be cast against you in PvE by bandits or tribes guards, who do not need to maintain a link to keep you rooted.
Kizarak have a special ability that allows them to inflict Root on their enemies with their spit attack. This is not a magical effect and thus Jungle resistance will not help you resist it. Creatures that are immune to Root spells similarly are not immune to this effect.
Creatures immune to Root
Root immunity only applies to the Offensive Affliction spell; not to Root caused by the Kizarak special ability.
Strangely, Root works on intelligent plants, even though it does nothing as they already can't move.