Dark green dragons, once they mature, appear to become an entirely different species. However, this isn’t true. Rather, they burrow underground and get nutrients from their vines. These vines are sometimes referred to as Dragon Grass. These dragons are very violent, and will use their vines to capture, kill, and eat anything that moves, as well as nearby plants. Luckily, their range is limited and they cannot use magic. Dark green dragons tend to be easy to spot since they usually kill all plants around them and thus are usually surrounded by a large clearing.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

As a hatchling, Mushroom Poisoning was captured by the Nightfang Alliance, a group of vampires that specializes in blackmail. There, he learned much about poisonous plants and fungi, sometimes by eavesdropping or watching one member slip a particular plant into an edible "gift" to another clan. Other times, he learned the hard way; fortunately, he didn't consume anything fatal. He was rescued by a Supernova patrol and returned to the Vinetooth.

Outwardly, Mushroom Poisoning seems polite and well-educated, but inwardly, he is a monster created by years of abuse and neglect. He will explode at the drop of a pin, and dragons he gets angry at are added to his 'kill list'. He is very suspicious toward everyone, especially outsiders, and sometimes slips unpleasant things into their meals for no reason at all. For some reason, he has never killed a clanmate or a Supernova dragon this way, although he shows great dislike for both.