Treant

A treant was a huge intelligent plant.

Biology
Although a treant's wood appeared to be solid like stone, it was filled with tubes that carried water from its roots to the areas where it was needed. Diseases such as tube wilt could affect these tubes and therefore the health of the treant.

Cormanthor
The treants in the forest of Cormanthor became hosts for rot grubs, which lived off rotting wood. If a treant was affected by tube wilt, it would open up a small crack and let the grubs in. The grubs would eat through all the rotten wood, eating the fungi causing the disease, and usually remain for good and tackle subsequent rot. This relationship did not harm either party, and older, larger treants might contain up to a hundred of these grubs.

In order to ward off predators such as woodchucks or wood-eating horses, the Cormanthor treants surrounded their roots with up to six Cormanthor violet fungi, whose roots tapped into the treant itself, using its sap as sustenance, and they would attempt to rot the flesh of any would-be predators.

In order to combat the threat of bark beetles and leaf ants, which could damage the treant, they encourage azmyths and large bats to make their homes in their branches.

Black squirrels fed on the female treants' shoots, which helped to limit the treants' population.

Rimwood
The rimwood area contained birch-like treants with very long roots to reach water. The sap contained an aroma of lemon and mint that could be used as a flavoring or perfume. Most had rot grubs, black squirrels, azmyths, and purple fungi.

Midwood
The midwood treants looked like golden willow and black locust trees. They protected themselves against brush rats by using the violet fungi. Their bark could be boiled to make either golden or black dye depending on their appearance.

Starwood
The starwood area contained treants that looked like dark brown oaks and grey elms. Half were peaceful, but the other half were quite hostile, although they did utilize rot grubs, fungi, black squirrels, and azmyths. The leaves of these treants would cure certain fevers and plagues.

Maztica
The treants that inhabited Maztica were fairly similar in appearance to those found in Faerûn, though they were not hostile to creatures foreign to their woods and instead preferred to ignore them. They considered themselves to be royalty of the forests they inhabited and expected other creatures to treat them as such, including giving them gifts.