- Ares, from his time in the Covenant Internal Affairs - "Treant"
Serving the Covenant war-machine, more treants were made. They were tasked with spying, becoming an intelligence network called the Roots of Núlananya. The seeds that have spread from these "spy treants" would become the more normal treant, those without the bits of warp matter to power their rift-making magic.
Treants of the realm are categorized by their tree type with Ironhue treants being those with a very high toughness, and the black oak treants of Logor having a high degree of strength, and the firebrand treants immune to fire, and so on. The warp matter of their ancestry has led to some becoming a corrupted form of a treant, like the dark treants of Gambriath.
The tree sap of treants, both living and dead, can be used to make potions like strength, fire resistance, healing, growth, giant strength, plant control, and many others. What type they can be used for depends on the treant type.