One of the uncommon plant based monsters, the Guardian Tree grows only in the city of Sia Marhu's North Cascade park, its population barely a few dozen individuals. It seems to be dependent on an unknown quality of the area, as attempts to cultivate specimens for study away from the park have failed, even near other rifts. They will not even grow within Sia Marhu if planted too far away from North Cascade.
Whilst this dependence would normally leave the trees vulnerable to extinction, they are incredibly hardy plants. Even if the Upper City of Sia Marhu had not issued protection of the trees for study purposes, it would be difficult to wipe them out. A mature tree is about twice the height of a tall man, with a bulbous trunk that divides into thin, curling branches tipped with bioluminescent fronds. The thick bark contains significant metal deposits to the point where the tree's surface has a shiny grey cast. This discourages even the toughest of grazers, whilst the vulnerable fronds are too high for most animals to reach. Those that can find the fronds quickly retreat, like tubeworms, inside the branches when bitten.
A guardian tree has no leaves and is not known to photosynthesise, although its deep roots (often several times the tree's length) gather water and minerals in the same way as a natural plants'. Instead, the guardian tree cultivates its own hive of stinging insects that live within its swollen trunk, in hives accessible from small holes in the side. These insects resemble small black honeybees and are only found in association with their trees. No eggs or larvae have ever been observed inside the hives, leading to theories that the tree itself generates them fully formed from the depths of its trunk. They will fly far from their home tree to gather food for their host, and should the tree become threatened they will swarm upon the interloper. Their stings are reusable and extremely painful; a swarm is more than capable of killing a healthy adult human through sheer numbers. They also distribute the guardian tree's seeds, which it also generates inside the hive, carring them away to plant them in suitable ground away from the parent. However they put no work into raising the seedlings, which must grow and generate their own hives in time.
The insects are fanatically devoted to their hosts and if kept away from their home tree will stop eating and die. Even transplanting them to another guardian tree will not save them; they are dependent on their original host and no other.