Reason given for below revision:
Turned much of it into a comment so I can make it public early.
Welcome to the flora and funga compendium! It lists and details all the known plants and mushrooms that are exclusive to Threa, so that do not exist on Earth already. While Earthly plants also exist in Threa and are mentioned across the region pages (e.g., oaks, strawberries, etc.), they are not featured here. You will have to find information on them elsewhere.
The list is not exhaustive. It only elaborates on elements that have come up in roleplay, stories, or similar.
C
Carcass Keeper
Grown specimen of this mushroom have a thin, up to 20 cm (7.8'') long stem with a large head on top. The mushroom head is up to 8 cm (3.1'') tall and shaped like an upside-down cone; the pointy end is connected to the stem and the top is flat. By overhanging the edge of the cone top a little, the fleshy roof of the mushroom protects the gills running down its sides. The entire mushroom is pale white in color.
The fungus is extremely toxic – lethal even in small doses. Consumption or getting it into a wound leads to poisoning, the former within minutes, the latter within seconds. Symptoms include agonizing headaches, strong nausea, and vomiting. The affected creature will succumb to pain-induced madness, ultimately dying of failure of the liver and nervous system.
Spores of the carcass keeper will stick to any creature that got near the mushroom, and they will of course be within any that eats it. They are harmless. Upon the creature's death, the spores will grow within and on the dead body. It does not matter whether the being died of carcass keeper poisoning or not. Corpses attract scavenger, and the mushroom assists in drawing them in by smelling potently of rotting meat. Eating the carrion comes at the risk of eating the young mushrooms or at least being covered in their spores – the cycle continues. Since some beasts have adapted to this by instinctively avoiding dead bodies that have an unnaturally strong smell or mushrooms already growing out of it, the fungus is often found on undisturbed carcasses, hence the name.
Carcass keepers grow wherever conditions are warm, humid, and shady. They dislike direct sunlight, and they cannot handle the cold. Outside of dead bodies, they also grow on dead plants and humus rich soil, just less well. Overall, they can be commonly found in the deep, gloomy woods of the Starless Jungle and in the wetlands of the Four-Faced Forests, especially in its western half. Populations disappear within the cold seasons and rapidly re-appear once temperatures increase and animals become more active, spreading the spores around.
Toxic as it is, the carcass keeper is popular among assassins and people that wish others a most painful death. It can also be used as a form of arrow poison. To poison someone's food, the mushroom must merely be included in the meal. Cooking the mushroom on a low temperature first is recommended; it gets rid of the smell, but it does not lessen its effects. Using it as a poison for blades requires alchemical work, which will yield a pale white, vicious liquid to spread on arrow tips, blades, or that can also be added to a meal or beverage.