Barkburr

Barkburr
Barkburrs are animate, poisonous Plants that spontaneously grow from trees when a spark of nature's magic takes root in the wood. They appear as limpet-like knots of bark and wood indistinguishable from ordinary tree burls. Barkburrs often act in defense of a grove or forest.
Some barkburrs cling to the trees from which they sprouted, while others slowly wander until they encounter creatures that threaten the forest's natural order. When a barkburr identifies such a creature, the barkburr leaps at the invader and injects it with a poisonous sap that quickly and painfully transforms the creature into a tree.