Belladonna

Belladonna, also known as wolfsbane, monkshood, or deadly nightshade, was a type of poisonous herb found in the Realms that was related to horseradish.
Being a type of flowering plant, belladonnas produced delicate purple bell-shaped flowers and black glossy berries. Its leaves and roots contained substance called atropine. If one were to cast speak with plants on some belladonnas, the plants would typically speak to the caster about lycanthropy and werewolves.
Belladonna were most famous for their ability to cure lycanthropy. However, they were also toxic - anyone eating them was likely to find themselves weakened physically. Consumption of their flowers was capable of inducing state of death-like sleep. Some claimed even the plant's touch was toxic and required protective gloves to harvest.
On Thalgriel Belladonna could be found in the forests around Lithryn, Arquen-Alda, and Burgmaester, beyond the Prime Material plane, belladonna could be found in both the Feywild and parts of the Domains of Dread.
Uses: If a victim bitten by a lycanthrope ate a sprig of belladonna within an hour of the bite, they had a chance of not contracting the disease. The belladonna, however, had to be relatively fresh, not picked any later than a week ago. Though consumption of belladonna worked equally as well for giants and giant-kin infected with lycanthropy, they needed to consume much larger amounts than the smaller humanoid races. Beyond its use with lycanthropy, it could be used to make a sedative.
Magic: Belladonna was used as a material component for a variety of charms, potions, spells, and obscure necromantic rituals. Because of this they were frequently harvested by hags and witches.
Conceal required an ointment, made in part with a pinch of powdered monkshood.
Oswald's mending required belladonna leaves and roots.
Protection from poison required a few belladonna leaves.
It was also used in gas bombs invented by the lycanthrope-hunting organization known as the Silver Stake.
Sublimate of belladonna plant when mixed with certain types of ashes was the main component in brewing the elixir of peerless focus.